Mercurial > octave-nkf
annotate doc/interpreter/func.txi @ 12592:732a568bf694 stable
Modify func.txi discussion of output arguments to include discussion of isargout.
| author | Rik <octave@nomad.inbox5.com> |
|---|---|
| date | Mon, 11 Apr 2011 19:03:32 -0700 |
| parents | 6f8ffe2c6f76 |
| children | 8c25df502846 |
| rev | line source |
|---|---|
| 11523 | 1 @c Copyright (C) 1996-2011 John W. Eaton |
| 7018 | 2 @c |
| 3 @c This file is part of Octave. | |
| 4 @c | |
| 5 @c Octave is free software; you can redistribute it and/or modify it | |
| 6 @c under the terms of the GNU General Public License as published by the | |
| 7 @c Free Software Foundation; either version 3 of the License, or (at | |
| 8 @c your option) any later version. | |
| 9 @c | |
| 10 @c Octave is distributed in the hope that it will be useful, but WITHOUT | |
| 11 @c ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 12 @c FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 13 @c for more details. | |
| 14 @c | |
| 15 @c You should have received a copy of the GNU General Public License | |
| 16 @c along with Octave; see the file COPYING. If not, see | |
| 17 @c <http://www.gnu.org/licenses/>. | |
| 3294 | 18 |
| 4167 | 19 @node Functions and Scripts |
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20 @chapter Functions and Scripts |
| 3294 | 21 @cindex defining functions |
| 22 @cindex user-defined functions | |
| 23 @cindex functions, user-defined | |
| 24 @cindex script files | |
| 25 | |
| 26 Complicated Octave programs can often be simplified by defining | |
| 27 functions. Functions can be defined directly on the command line during | |
| 28 interactive Octave sessions, or in external files, and can be called just | |
| 29 like built-in functions. | |
| 30 | |
| 31 @menu | |
| 32 * Defining Functions:: | |
| 33 * Multiple Return Values:: | |
| 34 * Variable-length Argument Lists:: | |
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35 * Ignoring Arguments:: |
| 3294 | 36 * Variable-length Return Lists:: |
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37 * Returning from a Function:: |
| 6510 | 38 * Default Arguments:: |
| 3294 | 39 * Function Files:: |
| 40 * Script Files:: | |
| 6638 | 41 * Function Handles Inline Functions and Anonymous Functions:: |
| 6549 | 42 * Commands:: |
| 3294 | 43 * Organization of Functions:: |
| 44 @end menu | |
| 45 | |
| 4167 | 46 @node Defining Functions |
| 3294 | 47 @section Defining Functions |
| 48 @cindex @code{function} statement | |
| 49 @cindex @code{endfunction} statement | |
| 50 | |
| 51 In its simplest form, the definition of a function named @var{name} | |
| 52 looks like this: | |
| 53 | |
| 54 @example | |
| 55 @group | |
| 56 function @var{name} | |
| 57 @var{body} | |
| 58 endfunction | |
| 59 @end group | |
| 60 @end example | |
| 61 | |
| 62 @noindent | |
| 63 A valid function name is like a valid variable name: a sequence of | |
| 64 letters, digits and underscores, not starting with a digit. Functions | |
| 65 share the same pool of names as variables. | |
| 66 | |
| 67 The function @var{body} consists of Octave statements. It is the | |
| 68 most important part of the definition, because it says what the function | |
| 69 should actually @emph{do}. | |
| 70 | |
| 71 For example, here is a function that, when executed, will ring the bell | |
| 72 on your terminal (assuming that it is possible to do so): | |
| 73 | |
| 74 @example | |
| 75 @group | |
| 76 function wakeup | |
| 77 printf ("\a"); | |
| 78 endfunction | |
| 79 @end group | |
| 80 @end example | |
| 81 | |
| 82 The @code{printf} statement (@pxref{Input and Output}) simply tells | |
| 83 Octave to print the string @code{"\a"}. The special character @samp{\a} | |
| 84 stands for the alert character (ASCII 7). @xref{Strings}. | |
| 85 | |
| 86 Once this function is defined, you can ask Octave to evaluate it by | |
| 87 typing the name of the function. | |
| 88 | |
| 89 Normally, you will want to pass some information to the functions you | |
| 90 define. The syntax for passing parameters to a function in Octave is | |
| 91 | |
| 92 @example | |
| 93 @group | |
| 94 function @var{name} (@var{arg-list}) | |
| 95 @var{body} | |
| 96 endfunction | |
| 97 @end group | |
| 98 @end example | |
| 99 | |
| 100 @noindent | |
| 101 where @var{arg-list} is a comma-separated list of the function's | |
| 102 arguments. When the function is called, the argument names are used to | |
| 103 hold the argument values given in the call. The list of arguments may | |
| 104 be empty, in which case this form is equivalent to the one shown above. | |
| 105 | |
| 106 To print a message along with ringing the bell, you might modify the | |
| 6510 | 107 @code{wakeup} to look like this: |
| 3294 | 108 |
| 109 @example | |
| 110 @group | |
| 111 function wakeup (message) | |
| 112 printf ("\a%s\n", message); | |
| 113 endfunction | |
| 114 @end group | |
| 115 @end example | |
| 116 | |
| 117 Calling this function using a statement like this | |
| 118 | |
| 119 @example | |
| 120 wakeup ("Rise and shine!"); | |
| 121 @end example | |
| 122 | |
| 123 @noindent | |
| 124 will cause Octave to ring your terminal's bell and print the message | |
| 125 @samp{Rise and shine!}, followed by a newline character (the @samp{\n} | |
| 126 in the first argument to the @code{printf} statement). | |
| 127 | |
| 128 In most cases, you will also want to get some information back from the | |
| 129 functions you define. Here is the syntax for writing a function that | |
| 130 returns a single value: | |
| 131 | |
| 132 @example | |
| 133 @group | |
| 134 function @var{ret-var} = @var{name} (@var{arg-list}) | |
| 135 @var{body} | |
| 136 endfunction | |
| 137 @end group | |
| 138 @end example | |
| 139 | |
| 140 @noindent | |
| 141 The symbol @var{ret-var} is the name of the variable that will hold the | |
| 142 value to be returned by the function. This variable must be defined | |
| 143 before the end of the function body in order for the function to return | |
| 144 a value. | |
| 145 | |
| 146 Variables used in the body of a function are local to the | |
| 147 function. Variables named in @var{arg-list} and @var{ret-var} are also | |
| 148 local to the function. @xref{Global Variables}, for information about | |
| 149 how to access global variables inside a function. | |
| 150 | |
| 151 For example, here is a function that computes the average of the | |
| 152 elements of a vector: | |
| 153 | |
| 154 @example | |
| 155 @group | |
| 156 function retval = avg (v) | |
| 157 retval = sum (v) / length (v); | |
| 158 endfunction | |
| 159 @end group | |
| 160 @end example | |
| 161 | |
| 162 If we had written @code{avg} like this instead, | |
| 163 | |
| 164 @example | |
| 165 @group | |
| 166 function retval = avg (v) | |
| 4029 | 167 if (isvector (v)) |
| 3294 | 168 retval = sum (v) / length (v); |
| 169 endif | |
| 170 endfunction | |
| 171 @end group | |
| 172 @end example | |
| 173 | |
| 174 @noindent | |
| 175 and then called the function with a matrix instead of a vector as the | |
| 176 argument, Octave would have printed an error message like this: | |
| 177 | |
| 178 @example | |
| 179 @group | |
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180 error: value on right hand side of assignment is undefined |
| 3294 | 181 @end group |
| 182 @end example | |
| 183 | |
| 184 @noindent | |
| 185 because the body of the @code{if} statement was never executed, and | |
| 186 @code{retval} was never defined. To prevent obscure errors like this, | |
| 187 it is a good idea to always make sure that the return variables will | |
| 188 always have values, and to produce meaningful error messages when | |
| 189 problems are encountered. For example, @code{avg} could have been | |
| 190 written like this: | |
| 191 | |
| 192 @example | |
| 193 @group | |
| 194 function retval = avg (v) | |
| 195 retval = 0; | |
| 4029 | 196 if (isvector (v)) |
| 3294 | 197 retval = sum (v) / length (v); |
| 198 else | |
| 199 error ("avg: expecting vector argument"); | |
| 200 endif | |
| 201 endfunction | |
| 202 @end group | |
| 203 @end example | |
| 204 | |
| 205 There is still one additional problem with this function. What if it is | |
| 206 called without an argument? Without additional error checking, Octave | |
| 207 will probably print an error message that won't really help you track | |
| 208 down the source of the error. To allow you to catch errors like this, | |
| 209 Octave provides each function with an automatic variable called | |
| 210 @code{nargin}. Each time a function is called, @code{nargin} is | |
| 211 automatically initialized to the number of arguments that have actually | |
| 212 been passed to the function. For example, we might rewrite the | |
| 213 @code{avg} function like this: | |
| 214 | |
| 215 @example | |
| 216 @group | |
| 217 function retval = avg (v) | |
| 218 retval = 0; | |
| 219 if (nargin != 1) | |
| 220 usage ("avg (vector)"); | |
| 221 endif | |
| 4029 | 222 if (isvector (v)) |
| 3294 | 223 retval = sum (v) / length (v); |
| 224 else | |
| 225 error ("avg: expecting vector argument"); | |
| 226 endif | |
| 227 endfunction | |
| 228 @end group | |
| 229 @end example | |
| 230 | |
| 231 Although Octave does not automatically report an error if you call a | |
| 232 function with more arguments than expected, doing so probably indicates | |
| 233 that something is wrong. Octave also does not automatically report an | |
| 234 error if a function is called with too few arguments, but any attempt to | |
| 235 use a variable that has not been given a value will result in an error. | |
| 236 To avoid such problems and to provide useful messages, we check for both | |
| 237 possibilities and issue our own error message. | |
| 238 | |
| 4700 | 239 @DOCSTRING(nargin) |
| 3294 | 240 |
| 6558 | 241 @DOCSTRING(inputname) |
| 242 | |
| 3371 | 243 @DOCSTRING(silent_functions) |
| 3294 | 244 |
| 4167 | 245 @node Multiple Return Values |
| 3294 | 246 @section Multiple Return Values |
| 247 | |
| 248 Unlike many other computer languages, Octave allows you to define | |
| 249 functions that return more than one value. The syntax for defining | |
| 250 functions that return multiple values is | |
| 251 | |
| 252 @example | |
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253 @group |
| 3294 | 254 function [@var{ret-list}] = @var{name} (@var{arg-list}) |
| 255 @var{body} | |
| 256 endfunction | |
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257 @end group |
| 3294 | 258 @end example |
| 259 | |
| 260 @noindent | |
| 261 where @var{name}, @var{arg-list}, and @var{body} have the same meaning | |
| 262 as before, and @var{ret-list} is a comma-separated list of variable | |
| 263 names that will hold the values returned from the function. The list of | |
| 264 return values must have at least one element. If @var{ret-list} has | |
| 265 only one element, this form of the @code{function} statement is | |
| 266 equivalent to the form described in the previous section. | |
| 267 | |
| 268 Here is an example of a function that returns two values, the maximum | |
| 269 element of a vector and the index of its first occurrence in the vector. | |
| 270 | |
| 271 @example | |
| 272 @group | |
| 273 function [max, idx] = vmax (v) | |
| 274 idx = 1; | |
| 275 max = v (idx); | |
| 276 for i = 2:length (v) | |
| 277 if (v (i) > max) | |
| 278 max = v (i); | |
| 279 idx = i; | |
| 280 endif | |
| 281 endfor | |
| 282 endfunction | |
| 283 @end group | |
| 284 @end example | |
| 285 | |
| 286 In this particular case, the two values could have been returned as | |
| 287 elements of a single array, but that is not always possible or | |
| 288 convenient. The values to be returned may not have compatible | |
| 289 dimensions, and it is often desirable to give the individual return | |
| 290 values distinct names. | |
| 291 | |
| 292 In addition to setting @code{nargin} each time a function is called, | |
| 293 Octave also automatically initializes @code{nargout} to the number of | |
| 294 values that are expected to be returned. This allows you to write | |
| 295 functions that behave differently depending on the number of values that | |
| 296 the user of the function has requested. The implicit assignment to the | |
| 297 built-in variable @code{ans} does not figure in the count of output | |
| 298 arguments, so the value of @code{nargout} may be zero. | |
| 299 | |
| 300 The @code{svd} and @code{lu} functions are examples of built-in | |
| 301 functions that behave differently depending on the value of | |
| 302 @code{nargout}. | |
| 303 | |
| 304 It is possible to write functions that only set some return values. For | |
| 305 example, calling the function | |
| 306 | |
| 307 @example | |
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308 @group |
| 3294 | 309 function [x, y, z] = f () |
| 310 x = 1; | |
| 311 z = 2; | |
| 312 endfunction | |
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313 @end group |
| 3294 | 314 @end example |
| 315 | |
| 316 @noindent | |
| 317 as | |
| 318 | |
| 319 @example | |
| 320 [a, b, c] = f () | |
| 321 @end example | |
| 322 | |
| 323 @noindent | |
| 324 produces: | |
| 325 | |
| 326 @example | |
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327 @group |
| 3294 | 328 a = 1 |
| 329 | |
| 330 b = [](0x0) | |
| 331 | |
| 332 c = 2 | |
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333 @end group |
| 3294 | 334 @end example |
| 335 | |
| 336 @noindent | |
| 6501 | 337 along with a warning. |
| 3294 | 338 |
| 4700 | 339 @DOCSTRING(nargout) |
| 3294 | 340 |
| 3371 | 341 @DOCSTRING(nargchk) |
| 3294 | 342 |
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343 @DOCSTRING(nargoutchk) |
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344 |
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345 @anchor{doc-varargin} @anchor{doc-varargout} |
| 4167 | 346 @node Variable-length Argument Lists |
| 3294 | 347 @section Variable-length Argument Lists |
| 4933 | 348 @cindex variable-length argument lists |
| 8567 | 349 @cindex @code{varargin} |
| 8072 | 350 |
| 6510 | 351 Sometimes the number of input arguments is not known when the function |
| 352 is defined. As an example think of a function that returns the smallest | |
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353 of all its input arguments. For example: |
| 6510 | 354 |
| 355 @example | |
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356 @group |
| 6510 | 357 a = smallest (1, 2, 3); |
| 358 b = smallest (1, 2, 3, 4); | |
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359 @end group |
| 6510 | 360 @end example |
| 361 | |
| 362 @noindent | |
| 363 In this example both @code{a} and @code{b} would be 1. One way to write | |
| 364 the @code{smallest} function is | |
| 365 | |
| 366 @example | |
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367 @group |
| 6510 | 368 function val = smallest (arg1, arg2, arg3, arg4, arg5) |
| 369 @var{body} | |
| 370 endfunction | |
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371 @end group |
| 6510 | 372 @end example |
| 373 | |
| 374 @noindent | |
| 375 and then use the value of @code{nargin} to determine which of the input | |
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376 arguments should be considered. The problem with this approach is |
| 6510 | 377 that it can only handle a limited number of input arguments. |
| 378 | |
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379 If the special parameter name @code{varargin} appears at the end of a |
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380 function parameter list it indicates that the function takes a variable |
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381 number of input arguments. Using @code{varargin} the function |
| 6510 | 382 looks like this |
| 383 | |
| 384 @example | |
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385 @group |
| 6510 | 386 function val = smallest (varargin) |
| 387 @var{body} | |
| 388 endfunction | |
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389 @end group |
| 6510 | 390 @end example |
| 391 | |
| 392 @noindent | |
| 393 In the function body the input arguments can be accessed through the | |
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394 variable @code{varargin}. This variable is a cell array containing |
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395 all the input arguments. @xref{Cell Arrays}, for details on working |
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396 with cell arrays. The @code{smallest} function can now be defined |
| 6510 | 397 like this |
| 398 | |
| 399 @example | |
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400 @group |
| 6510 | 401 function val = smallest (varargin) |
| 402 val = min ([varargin@{:@}]); | |
| 403 endfunction | |
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404 @end group |
| 6510 | 405 @end example |
| 406 | |
| 407 @noindent | |
| 408 This implementation handles any number of input arguments, but it's also | |
| 409 a very simple solution to the problem. | |
| 410 | |
| 411 A slightly more complex example of @code{varargin} is a function | |
| 412 @code{print_arguments} that prints all input arguments. Such a function | |
| 413 can be defined like this | |
| 414 | |
| 415 @example | |
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416 @group |
| 6510 | 417 function print_arguments (varargin) |
| 418 for i = 1:length (varargin) | |
| 419 printf ("Input argument %d: ", i); | |
| 420 disp (varargin@{i@}); | |
| 421 endfor | |
| 422 endfunction | |
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423 @end group |
| 6510 | 424 @end example |
| 425 | |
| 426 @noindent | |
| 427 This function produces output like this | |
| 428 | |
| 429 @example | |
| 430 @group | |
| 431 print_arguments (1, "two", 3); | |
| 432 @print{} Input argument 1: 1 | |
| 433 @print{} Input argument 2: two | |
| 434 @print{} Input argument 3: 3 | |
| 435 @end group | |
| 436 @end example | |
| 3294 | 437 |
| 6558 | 438 @DOCSTRING(parseparams) |
| 439 | |
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440 @node Ignoring Arguments |
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441 @section Ignoring Arguments |
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442 |
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443 In the formal argument list, it is possible to use the dummy placeholder |
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444 @code{~} instead of a name. This indicates that the corresponding argument |
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445 value should be ignored and not stored to any variable. |
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446 |
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447 @example |
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448 @group |
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449 function val = pick2nd (~, arg2) |
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450 val = arg2; |
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451 endfunction |
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452 @end group |
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453 @end example |
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454 |
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455 The value of @code{nargin} is not affected by using this declaration. |
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456 |
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457 Return arguments can also be ignored using the same syntax. Functions may |
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458 take advantage of ignored outputs to reduce the number of calculations |
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459 performed. To do so, use the @code{isargout} function to query whether the |
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460 output argument is wanted. For example: |
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461 |
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462 @example |
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463 @group |
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464 function [out1, out2] = long_function (x, y, z) |
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465 if (isargout (1)) |
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466 ## Long calculation |
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467 @dots{} |
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468 out1 = result; |
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469 endif |
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470 @dots{} |
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471 endfunction |
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472 @end group |
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473 @end example |
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474 |
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475 @DOCSTRING(isargout) |
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476 |
| 4167 | 477 @node Variable-length Return Lists |
| 3294 | 478 @section Variable-length Return Lists |
| 4933 | 479 @cindex variable-length return lists |
| 8567 | 480 @cindex @code{varargout} |
| 8072 | 481 |
| 6510 | 482 It is possible to return a variable number of output arguments from a |
| 483 function using a syntax that's similar to the one used with the | |
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484 special @code{varargin} parameter name. To let a function return a |
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485 variable number of output arguments the special output parameter name |
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486 @code{varargout} is used. As with @code{varargin}, @code{varargout} is |
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487 a cell array that will contain the requested output arguments. |
| 6510 | 488 |
| 489 As an example the following function sets the first output argument to | |
| 490 1, the second to 2, and so on. | |
| 491 | |
| 492 @example | |
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493 @group |
| 6510 | 494 function varargout = one_to_n () |
| 495 for i = 1:nargout | |
| 496 varargout@{i@} = i; | |
| 497 endfor | |
| 498 endfunction | |
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499 @end group |
| 6510 | 500 @end example |
| 501 | |
| 502 @noindent | |
| 503 When called this function returns values like this | |
| 504 | |
| 505 @example | |
| 506 @group | |
| 507 [a, b, c] = one_to_n () | |
| 508 @result{} a = 1 | |
| 509 @result{} b = 2 | |
| 510 @result{} c = 3 | |
| 511 @end group | |
| 512 @end example | |
| 3294 | 513 |
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514 If @code{varargin} (@code{varargout}) does not appear as the last |
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515 element of the input (output) parameter list, then it is not special, |
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516 and is handled the same as any other parameter name. |
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517 |
| 6558 | 518 @DOCSTRING(deal) |
| 519 | |
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520 @node Returning from a Function |
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521 @section Returning from a Function |
| 3294 | 522 |
| 523 The body of a user-defined function can contain a @code{return} statement. | |
| 524 This statement returns control to the rest of the Octave program. It | |
| 525 looks like this: | |
| 526 | |
| 527 @example | |
| 528 return | |
| 529 @end example | |
| 530 | |
| 531 Unlike the @code{return} statement in C, Octave's @code{return} | |
| 532 statement cannot be used to return a value from a function. Instead, | |
| 533 you must assign values to the list of return variables that are part of | |
| 534 the @code{function} statement. The @code{return} statement simply makes | |
| 535 it easier to exit a function from a deeply nested loop or conditional | |
| 536 statement. | |
| 537 | |
| 538 Here is an example of a function that checks to see if any elements of a | |
| 539 vector are nonzero. | |
| 540 | |
| 541 @example | |
| 542 @group | |
| 543 function retval = any_nonzero (v) | |
| 544 retval = 0; | |
| 545 for i = 1:length (v) | |
| 546 if (v (i) != 0) | |
| 547 retval = 1; | |
| 548 return; | |
| 549 endif | |
| 550 endfor | |
| 551 printf ("no nonzero elements found\n"); | |
| 552 endfunction | |
| 553 @end group | |
| 554 @end example | |
| 555 | |
| 556 Note that this function could not have been written using the | |
| 557 @code{break} statement to exit the loop once a nonzero value is found | |
| 558 without adding extra logic to avoid printing the message if the vector | |
| 559 does contain a nonzero element. | |
| 560 | |
| 11547 | 561 @deftypefn {Keyword} {} return |
| 3294 | 562 When Octave encounters the keyword @code{return} inside a function or |
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563 script, it returns control to the caller immediately. At the top level, |
| 3294 | 564 the return statement is ignored. A @code{return} statement is assumed |
| 565 at the end of every function definition. | |
| 11547 | 566 @end deftypefn |
| 3294 | 567 |
| 6510 | 568 @node Default Arguments |
| 569 @section Default Arguments | |
| 570 @cindex default arguments | |
| 571 | |
| 572 Since Octave supports variable number of input arguments, it is very useful | |
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573 to assign default values to some input arguments. When an input argument |
| 6510 | 574 is declared in the argument list it is possible to assign a default |
| 575 value to the argument like this | |
| 576 | |
| 577 @example | |
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578 @group |
| 6510 | 579 function @var{name} (@var{arg1} = @var{val1}, @dots{}) |
| 580 @var{body} | |
| 581 endfunction | |
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582 @end group |
| 6510 | 583 @end example |
| 584 | |
| 585 @noindent | |
| 586 If no value is assigned to @var{arg1} by the user, it will have the | |
| 587 value @var{val1}. | |
| 588 | |
| 589 As an example, the following function implements a variant of the classic | |
| 590 ``Hello, World'' program. | |
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591 |
| 6510 | 592 @example |
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593 @group |
| 6510 | 594 function hello (who = "World") |
| 595 printf ("Hello, %s!\n", who); | |
| 596 endfunction | |
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597 @end group |
| 6510 | 598 @end example |
| 599 | |
| 600 @noindent | |
| 601 When called without an input argument the function prints the following | |
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602 |
| 6510 | 603 @example |
| 604 @group | |
| 605 hello (); | |
| 606 @print{} Hello, World! | |
| 607 @end group | |
| 608 @end example | |
| 609 | |
| 610 @noindent | |
| 611 and when it's called with an input argument it prints the following | |
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612 |
| 6510 | 613 @example |
| 614 @group | |
| 615 hello ("Beautiful World of Free Software"); | |
| 616 @print{} Hello, Beautiful World of Free Software! | |
| 617 @end group | |
| 618 @end example | |
| 619 | |
| 620 Sometimes it is useful to explicitly tell Octave to use the default value | |
| 621 of an input argument. This can be done writing a @samp{:} as the value | |
| 622 of the input argument when calling the function. | |
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623 |
| 6510 | 624 @example |
| 625 @group | |
| 626 hello (:); | |
| 627 @print{} Hello, World! | |
| 628 @end group | |
| 629 @end example | |
| 630 | |
| 4167 | 631 @node Function Files |
| 3294 | 632 @section Function Files |
| 633 @cindex function file | |
| 634 | |
| 635 Except for simple one-shot programs, it is not practical to have to | |
| 636 define all the functions you need each time you need them. Instead, you | |
| 637 will normally want to save them in a file so that you can easily edit | |
| 638 them, and save them for use at a later time. | |
| 639 | |
| 640 Octave does not require you to load function definitions from files | |
| 641 before using them. You simply need to put the function definitions in a | |
| 642 place where Octave can find them. | |
| 643 | |
| 644 When Octave encounters an identifier that is undefined, it first looks | |
| 645 for variables or functions that are already compiled and currently | |
| 646 listed in its symbol table. If it fails to find a definition there, it | |
| 6556 | 647 searches a list of directories (the @dfn{path}) for files ending in |
| 6554 | 648 @file{.m} that have the same base name as the undefined |
| 649 identifier.@footnote{The @samp{.m} suffix was chosen for compatibility | |
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650 with @sc{matlab}.} Once Octave finds a file with a name that matches, |
| 6554 | 651 the contents of the file are read. If it defines a @emph{single} |
| 652 function, it is compiled and executed. @xref{Script Files}, for more | |
| 653 information about how you can define more than one function in a single | |
| 654 file. | |
| 3294 | 655 |
| 656 When Octave defines a function from a function file, it saves the full | |
| 6554 | 657 name of the file it read and the time stamp on the file. If the time |
| 658 stamp on the file changes, Octave may reload the file. When Octave is | |
| 659 running interactively, time stamp checking normally happens at most once | |
| 660 each time Octave prints the prompt. Searching for new function | |
| 661 definitions also occurs if the current working directory changes. | |
| 3294 | 662 |
| 663 Checking the time stamp allows you to edit the definition of a function | |
| 664 while Octave is running, and automatically use the new function | |
| 6554 | 665 definition without having to restart your Octave session. |
| 3294 | 666 |
| 667 To avoid degrading performance unnecessarily by checking the time stamps | |
| 668 on functions that are not likely to change, Octave assumes that function | |
| 669 files in the directory tree | |
| 670 @file{@var{octave-home}/share/octave/@var{version}/m} | |
| 671 will not change, so it doesn't have to check their time stamps every time the | |
| 672 functions defined in those files are used. This is normally a very good | |
| 673 assumption and provides a significant improvement in performance for the | |
| 674 function files that are distributed with Octave. | |
| 675 | |
| 676 If you know that your own function files will not change while you are | |
| 6554 | 677 running Octave, you can improve performance by calling |
| 678 @code{ignore_function_time_stamp ("all")}, so that Octave will | |
| 679 ignore the time stamps for all function files. Passing | |
| 680 @code{"system"} to this function resets the default behavior. | |
| 3294 | 681 |
| 5775 | 682 @c FIXME -- note about time stamps on files in NFS environments? |
| 3294 | 683 |
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684 @DOCSTRING(edit) |
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685 |
| 6549 | 686 @DOCSTRING(mfilename) |
| 687 | |
| 6638 | 688 @DOCSTRING(ignore_function_time_stamp) |
| 689 | |
| 690 @menu | |
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691 * Manipulating the Load Path:: |
| 6638 | 692 * Subfunctions:: |
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693 * Private Functions:: |
| 6638 | 694 * Overloading and Autoloading:: |
| 695 * Function Locking:: | |
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696 * Function Precedence:: |
| 6638 | 697 @end menu |
| 698 | |
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699 @node Manipulating the Load Path |
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700 @subsection Manipulating the Load Path |
| 6638 | 701 |
| 8828 | 702 When a function is called, Octave searches a list of directories for |
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703 a file that contains the function declaration. This list of directories |
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704 is known as the load path. By default the load path contains |
| 6638 | 705 a list of directories distributed with Octave plus the current |
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706 working directory. To see your current load path call the @code{path} |
| 6638 | 707 function without any input or output arguments. |
| 708 | |
| 709 It is possible to add or remove directories to or from the load path | |
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710 using @code{addpath} and @code{rmpath}. As an example, the following |
| 6638 | 711 code adds @samp{~/Octave} to the load path. |
| 712 | |
| 713 @example | |
| 714 addpath("~/Octave") | |
| 715 @end example | |
| 716 | |
| 717 @noindent | |
| 718 After this the directory @samp{~/Octave} will be searched for functions. | |
| 719 | |
| 6502 | 720 @DOCSTRING(addpath) |
| 721 | |
| 722 @DOCSTRING(genpath) | |
| 723 | |
| 724 @DOCSTRING(rmpath) | |
| 725 | |
| 726 @DOCSTRING(savepath) | |
| 727 | |
| 6477 | 728 @DOCSTRING(path) |
| 3294 | 729 |
| 6502 | 730 @DOCSTRING(pathdef) |
| 731 | |
| 732 @DOCSTRING(pathsep) | |
| 733 | |
| 3428 | 734 @DOCSTRING(rehash) |
| 735 | |
| 736 @DOCSTRING(file_in_loadpath) | |
| 737 | |
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738 @DOCSTRING(restoredefaultpath) |
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739 |
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740 @DOCSTRING(command_line_path) |
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741 |
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742 @DOCSTRING(find_dir_in_path) |
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743 |
| 6556 | 744 @node Subfunctions |
| 745 @subsection Subfunctions | |
| 746 | |
| 747 A function file may contain secondary functions called | |
| 748 @dfn{subfunctions}. These secondary functions are only visible to the | |
| 749 other functions in the same function file. For example, a file | |
| 750 @file{f.m} containing | |
| 751 | |
| 752 @example | |
| 753 @group | |
| 754 function f () | |
| 755 printf ("in f, calling g\n"); | |
| 756 g () | |
| 757 endfunction | |
| 758 function g () | |
| 759 printf ("in g, calling h\n"); | |
| 6638 | 760 h () |
| 6556 | 761 endfunction |
| 762 function h () | |
| 763 printf ("in h\n") | |
| 764 endfunction | |
| 765 @end group | |
| 766 @end example | |
| 767 | |
| 768 @noindent | |
| 769 defines a main function @code{f} and two subfunctions. The | |
| 770 subfunctions @code{g} and @code{h} may only be called from the main | |
| 771 function @code{f} or from the other subfunctions, but not from outside | |
| 772 the file @file{f.m}. | |
| 773 | |
|
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774 @node Private Functions |
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775 @subsection Private Functions |
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776 |
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777 In many cases one function needs to access one or more helper |
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778 functions. If the helper function is limited to the scope of a single |
|
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779 function, then subfunctions as discussed above might be used. However, |
|
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780 if a single helper function is used by more than one function, then |
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781 this is no longer possible. In this case the helper functions might |
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782 be placed in a subdirectory, called "private", of the directory in which |
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783 the functions needing access to this helper function are found. |
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784 |
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785 As a simple example, consider a function @code{func1}, that calls a helper |
|
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786 function @code{func2} to do much of the work. For example: |
|
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787 |
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788 @example |
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789 @group |
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790 function y = func1 (x) |
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791 y = func2 (x); |
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792 endfunction |
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793 @end group |
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794 @end example |
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795 |
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796 @noindent |
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797 Then if the path to @code{func1} is @code{<directory>/func1.m}, and if |
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798 @code{func2} is found in the directory @code{<directory>/private/func2.m}, |
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799 then @code{func2} is only available for use of the functions, like |
|
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800 @code{func1}, that are found in @code{<directory>}. |
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801 |
| 6635 | 802 @node Overloading and Autoloading |
| 803 @subsection Overloading and Autoloading | |
| 804 | |
|
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805 Functions can be overloaded to work with different input arguments. For |
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806 example, the operator '+' has been overloaded in Octave to work with single, |
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807 double, uint8, int32, and many other arguments. The preferred way to overload |
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808 functions is through classes and object oriented programming |
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809 (@pxref{Function Overloading}). Occasionally, however, one needs to undo |
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810 user overloading and call the default function associated with a specific |
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811 type. The @code{builtin} function exists for this purpose. |
| 6635 | 812 |
| 813 @DOCSTRING(builtin) | |
| 814 | |
| 815 A single dynamically linked file might define several | |
|
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816 functions. However, as Octave searches for functions based on the |
| 6635 | 817 functions filename, Octave needs a manner in which to find each of the |
|
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818 functions in the dynamically linked file. On operating systems that |
| 6635 | 819 support symbolic links, it is possible to create a symbolic link to the |
| 820 original file for each of the functions which it contains. | |
| 821 | |
| 822 However, there is at least one well known operating system that doesn't | |
|
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823 support symbolic links. Making copies of the original file for each of |
| 8828 | 824 the functions is undesirable as it increases the |
|
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825 amount of disk space used by Octave. Instead Octave supplies the |
| 6635 | 826 @code{autoload} function, that permits the user to define in which |
| 827 file a certain function will be found. | |
| 828 | |
| 829 @DOCSTRING(autoload) | |
| 830 | |
| 831 @node Function Locking | |
| 832 @subsection Function Locking | |
| 833 | |
| 834 It is sometime desirable to lock a function into memory with the | |
|
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835 @code{mlock} function. This is typically used for dynamically linked |
| 6899 | 836 functions in Oct-files or mex-files that contain some initialization, |
| 837 and it is desirable that calling @code{clear} does not remove this | |
| 6635 | 838 initialization. |
| 839 | |
| 6899 | 840 As an example, |
| 841 | |
| 842 @example | |
| 843 mlock ("my_function"); | |
| 844 @end example | |
| 845 | |
| 846 @noindent | |
| 847 prevents @code{my_function} from being removed from memory, even if | |
| 848 @code{clear} is called. It is possible to determine if a function is | |
| 849 locked into memory with the @code{mislocked}, and to unlock a function | |
| 850 with @code{munlock}, which the following illustrates. | |
| 851 | |
| 852 @example | |
| 853 @group | |
| 854 mlock ("my_function"); | |
| 855 mislocked ("my_function") | |
| 856 @result{} ans = 1 | |
| 857 munlock ("my_function"); | |
| 858 mislocked ("my_function") | |
| 859 @result{} ans = 0 | |
| 860 @end group | |
| 861 @end example | |
| 862 | |
| 863 A common use of @code{mlock} is to prevent persistent variables from | |
| 8828 | 864 being removed from memory, as the following example shows: |
| 6899 | 865 |
| 866 @example | |
| 867 @group | |
| 868 function count_calls() | |
| 869 persistent calls = 0; | |
| 7031 | 870 printf ("'count_calls' has been called %d times\n", |
| 871 ++calls); | |
| 6899 | 872 endfunction |
| 873 mlock ("count_calls"); | |
| 874 | |
| 875 count_calls (); | |
| 876 @print{} 'count_calls' has been called 1 times | |
| 877 | |
| 878 clear count_calls | |
| 879 count_calls (); | |
| 880 @print{} 'count_calls' has been called 2 times | |
| 881 @end group | |
| 882 @end example | |
| 883 | |
| 884 @noindent | |
| 885 It is, however, often inconvenient to lock a function from the prompt, | |
| 886 so it is also possible to lock a function from within its body. This | |
| 887 is simply done by calling @code{mlock} from within the function. | |
| 888 | |
| 889 @example | |
| 890 @group | |
| 891 function count_calls () | |
| 892 mlock (); | |
| 893 persistent calls = 0; | |
| 7031 | 894 printf ("'count_calls' has been called %d times\n", |
| 895 ++calls); | |
| 6899 | 896 endfunction |
| 897 @end group | |
| 898 @end example | |
| 899 | |
| 900 @code{mlock} might equally be used to prevent changes to a function from having | |
| 6635 | 901 effect in Octave, though a similar effect can be had with the |
| 902 @code{ignore_function_time_stamp} function. | |
| 903 | |
| 904 @DOCSTRING(mlock) | |
| 905 | |
| 906 @DOCSTRING(munlock) | |
| 907 | |
| 908 @DOCSTRING(mislocked) | |
| 909 | |
|
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910 @node Function Precedence |
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911 @subsection Function Precedence |
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912 |
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913 Given the numerous different ways that Octave can define a function, it |
|
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914 is possible and even likely that multiple versions of a function, might be |
|
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915 defined within a particular scope. The precedence of which function will be |
|
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916 used within a particular scope is given by |
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917 |
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918 @enumerate 1 |
|
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919 @item Subfunction |
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920 A subfunction with the required function name in the given scope. |
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921 |
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922 @item Private function |
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923 A function defined within a private directory of the directory |
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924 which contains the current function. |
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925 |
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926 @item Class constructor |
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927 A function that constuctors a user class as defined in chapter |
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928 @ref{Object Oriented Programming}. |
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929 |
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930 @item Class method |
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931 An overloaded function of a class as in chapter |
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932 @ref{Object Oriented Programming}. |
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933 |
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934 @item Legacy Dispatch |
|
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935 An overloaded function as defined by @code{dispatch}. |
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936 |
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937 @item Command-line Function |
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938 A function that has been defined on the command-line. |
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939 |
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940 @item Autoload function |
| 8235 | 941 A function that is marked as autoloaded with @xref{doc-autoload}. |
|
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942 |
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943 @item A Function on the Path |
|
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944 A function that can be found on the users load-path. There can also be |
|
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945 Oct-file, mex-file or m-file versions of this function and the precedence |
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946 between these versions are in that order. |
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947 |
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948 @item Built-in function |
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949 A function that is builtin to Octave itself such as @code{numel}, |
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950 @code{size}, etc. |
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951 @end enumerate |
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952 |
| 4167 | 953 @node Script Files |
| 3294 | 954 @section Script Files |
| 955 | |
| 956 A script file is a file containing (almost) any sequence of Octave | |
| 957 commands. It is read and evaluated just as if you had typed each | |
| 958 command at the Octave prompt, and provides a convenient way to perform a | |
| 959 sequence of commands that do not logically belong inside a function. | |
| 960 | |
| 961 Unlike a function file, a script file must @emph{not} begin with the | |
| 962 keyword @code{function}. If it does, Octave will assume that it is a | |
| 963 function file, and that it defines a single function that should be | |
| 964 evaluated as soon as it is defined. | |
| 965 | |
| 966 A script file also differs from a function file in that the variables | |
| 967 named in a script file are not local variables, but are in the same | |
| 968 scope as the other variables that are visible on the command line. | |
| 969 | |
| 970 Even though a script file may not begin with the @code{function} | |
| 971 keyword, it is possible to define more than one function in a single | |
| 972 script file and load (but not execute) all of them at once. To do | |
| 973 this, the first token in the file (ignoring comments and other white | |
| 974 space) must be something other than @code{function}. If you have no | |
| 975 other statements to evaluate, you can use a statement that has no | |
| 976 effect, like this: | |
| 977 | |
| 978 @example | |
| 979 @group | |
| 980 # Prevent Octave from thinking that this | |
| 981 # is a function file: | |
| 982 | |
| 983 1; | |
| 984 | |
| 985 # Define function one: | |
| 986 | |
| 987 function one () | |
|
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|
988 @dots{} |
| 3294 | 989 @end group |
| 990 @end example | |
| 991 | |
| 992 To have Octave read and compile these functions into an internal form, | |
| 6638 | 993 you need to make sure that the file is in Octave's load path |
| 6477 | 994 (accessible through the @code{path} function), then simply type the |
| 995 base name of the file that contains the commands. (Octave uses the | |
| 996 same rules to search for script files as it does to search for | |
| 997 function files.) | |
| 3294 | 998 |
| 999 If the first token in a file (ignoring comments) is @code{function}, | |
| 1000 Octave will compile the function and try to execute it, printing a | |
| 1001 message warning about any non-whitespace characters that appear after | |
| 1002 the function definition. | |
| 1003 | |
| 1004 Note that Octave does not try to look up the definition of any identifier | |
| 1005 until it needs to evaluate it. This means that Octave will compile the | |
| 1006 following statements if they appear in a script file, or are typed at | |
| 1007 the command line, | |
| 1008 | |
| 1009 @example | |
| 1010 @group | |
| 1011 # not a function file: | |
| 1012 1; | |
| 1013 function foo () | |
| 1014 do_something (); | |
| 1015 endfunction | |
| 1016 function do_something () | |
| 1017 do_something_else (); | |
| 1018 endfunction | |
| 1019 @end group | |
| 1020 @end example | |
| 1021 | |
| 1022 @noindent | |
| 1023 even though the function @code{do_something} is not defined before it is | |
| 1024 referenced in the function @code{foo}. This is not an error because | |
| 1025 Octave does not need to resolve all symbols that are referenced by a | |
| 1026 function until the function is actually evaluated. | |
| 1027 | |
| 1028 Since Octave doesn't look for definitions until they are needed, the | |
| 1029 following code will always print @samp{bar = 3} whether it is typed | |
| 1030 directly on the command line, read from a script file, or is part of a | |
| 1031 function body, even if there is a function or script file called | |
| 6477 | 1032 @file{bar.m} in Octave's path. |
| 3294 | 1033 |
| 1034 @example | |
| 1035 @group | |
| 1036 eval ("bar = 3"); | |
| 1037 bar | |
| 1038 @end group | |
| 1039 @end example | |
| 1040 | |
| 1041 Code like this appearing within a function body could fool Octave if | |
| 1042 definitions were resolved as the function was being compiled. It would | |
| 1043 be virtually impossible to make Octave clever enough to evaluate this | |
| 1044 code in a consistent fashion. The parser would have to be able to | |
| 1045 perform the call to @code{eval} at compile time, and that would be | |
| 1046 impossible unless all the references in the string to be evaluated could | |
| 1047 also be resolved, and requiring that would be too restrictive (the | |
| 1048 string might come from user input, or depend on things that are not | |
| 1049 known until the function is evaluated). | |
| 1050 | |
| 1051 Although Octave normally executes commands from script files that have | |
| 1052 the name @file{@var{file}.m}, you can use the function @code{source} to | |
| 1053 execute commands from any file. | |
| 1054 | |
| 3371 | 1055 @DOCSTRING(source) |
| 3294 | 1056 |
| 6638 | 1057 @node Function Handles Inline Functions and Anonymous Functions |
| 1058 @section Function Handles, Inline Functions, and Anonymous Functions | |
| 4933 | 1059 @cindex handle, function handles |
| 1060 @cindex inline, inline functions | |
| 6638 | 1061 @cindex anonymous functions |
| 4933 | 1062 |
| 6638 | 1063 It can be very convenient store a function in a variable so that it |
|
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1064 can be passed to a different function. For example, a function that |
|
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1065 performs numerical minimization needs access to the function that |
|
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|
1066 should be minimized. |
| 4933 | 1067 |
| 1068 @menu | |
| 1069 * Function Handles:: | |
| 6554 | 1070 * Anonymous Functions:: |
| 4933 | 1071 * Inline Functions:: |
| 1072 @end menu | |
| 1073 | |
| 1074 @node Function Handles | |
| 1075 @subsection Function Handles | |
| 1076 | |
| 6554 | 1077 A function handle is a pointer to another function and is defined with |
| 1078 the syntax | |
| 1079 | |
| 1080 @example | |
| 1081 @@@var{function-name} | |
| 1082 @end example | |
| 1083 | |
| 1084 @noindent | |
|
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|
1085 For example, |
| 6554 | 1086 |
| 1087 @example | |
| 6556 | 1088 f = @@sin; |
| 6554 | 1089 @end example |
| 1090 | |
| 1091 @noindent | |
|
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1092 creates a function handle called @code{f} that refers to the |
| 6554 | 1093 function @code{sin}. |
| 1094 | |
| 1095 Function handles are used to call other functions indirectly, or to pass | |
| 1096 a function as an argument to another function like @code{quad} or | |
|
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1097 @code{fsolve}. For example: |
| 6554 | 1098 |
| 1099 @example | |
|
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1100 @group |
| 6556 | 1101 f = @@sin; |
| 6554 | 1102 quad (f, 0, pi) |
| 6929 | 1103 @result{} 2 |
|
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|
1104 @end group |
| 6554 | 1105 @end example |
| 1106 | |
| 1107 You may use @code{feval} to call a function using function handle, or | |
| 6570 | 1108 simply write the name of the function handle followed by an argument |
| 6554 | 1109 list. If there are no arguments, you must use an empty argument list |
|
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1110 @samp{()}. For example: |
| 6554 | 1111 |
| 1112 @example | |
|
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|
1113 @group |
| 6556 | 1114 f = @@sin; |
| 6554 | 1115 feval (f, pi/4) |
| 6570 | 1116 @result{} 0.70711 |
| 6554 | 1117 f (pi/4) |
| 6570 | 1118 @result{} 0.70711 |
|
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|
1119 @end group |
| 6554 | 1120 @end example |
| 1121 | |
| 4933 | 1122 @DOCSTRING(functions) |
| 1123 | |
| 1124 @DOCSTRING(func2str) | |
| 1125 | |
| 1126 @DOCSTRING(str2func) | |
| 1127 | |
| 6570 | 1128 @node Anonymous Functions |
| 6554 | 1129 @subsection Anonymous Functions |
| 1130 | |
| 1131 Anonymous functions are defined using the syntax | |
| 1132 | |
| 1133 @example | |
| 1134 @@(@var{argument-list}) @var{expression} | |
| 1135 @end example | |
| 1136 | |
| 1137 @noindent | |
| 1138 Any variables that are not found in the argument list are inherited from | |
| 1139 the enclosing scope. Anonymous functions are useful for creating simple | |
| 1140 unnamed functions from expressions or for wrapping calls to other | |
| 1141 functions to adapt them for use by functions like @code{quad}. For | |
| 1142 example, | |
| 1143 | |
| 1144 @example | |
|
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|
1145 @group |
| 6554 | 1146 f = @@(x) x.^2; |
| 1147 quad (f, 0, 10) | |
| 6570 | 1148 @result{} 333.33 |
|
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|
1149 @end group |
| 6554 | 1150 @end example |
| 1151 | |
| 1152 @noindent | |
| 1153 creates a simple unnamed function from the expression @code{x.^2} and | |
| 1154 passes it to @code{quad}, | |
| 1155 | |
| 1156 @example | |
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1157 @group |
| 6554 | 1158 quad (@@(x) sin (x), 0, pi) |
| 6933 | 1159 @result{} 2 |
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|
1160 @end group |
| 6554 | 1161 @end example |
| 1162 | |
| 1163 @noindent | |
| 1164 wraps another function, and | |
| 1165 | |
| 1166 @example | |
|
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|
1167 @group |
| 6554 | 1168 a = 1; |
| 1169 b = 2; | |
| 1170 quad (@@(x) betainc (x, a, b), 0, 0.4) | |
| 6929 | 1171 @result{} 0.13867 |
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1172 @end group |
| 6554 | 1173 @end example |
| 1174 | |
| 1175 @noindent | |
| 1176 adapts a function with several parameters to the form required by | |
| 1177 @code{quad}. In this example, the values of @var{a} and @var{b} that | |
| 1178 are passed to @code{betainc} are inherited from the current | |
| 1179 environment. | |
| 1180 | |
| 4933 | 1181 @node Inline Functions |
| 1182 @subsection Inline Functions | |
| 1183 | |
| 6638 | 1184 An inline function is created from a string containing the function |
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1185 body using the @code{inline} function. The following code defines the |
| 6638 | 1186 function @math{f(x) = x^2 + 2}. |
| 1187 | |
| 1188 @example | |
| 1189 f = inline("x^2 + 2"); | |
| 1190 @end example | |
| 1191 | |
| 1192 @noindent | |
| 1193 After this it is possible to evaluate @math{f} at any @math{x} by | |
| 1194 writing @code{f(x)}. | |
| 1195 | |
| 4933 | 1196 @DOCSTRING(inline) |
| 1197 | |
| 1198 @DOCSTRING(argnames) | |
| 1199 | |
| 1200 @DOCSTRING(formula) | |
| 1201 | |
| 1202 @DOCSTRING(vectorize) | |
| 1203 | |
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1204 @DOCSTRING(symvar) |
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1205 |
| 6549 | 1206 @node Commands |
| 1207 @section Commands | |
| 1208 | |
| 6638 | 1209 Commands are a special class of functions that only accept string |
|
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1210 input arguments. A command can be called as an ordinary function, but |
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1211 it can also be called without the parentheses. For example, |
| 6638 | 1212 |
| 1213 @example | |
| 1214 my_command hello world | |
| 1215 @end example | |
| 1216 | |
| 1217 @noindent | |
|
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1218 is equivalent to |
| 6638 | 1219 |
| 1220 @example | |
| 1221 my_command("hello", "world") | |
| 1222 @end example | |
| 1223 | |
|
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1224 @noindent |
| 6638 | 1225 The general form of a command call is |
| 1226 | |
| 1227 @example | |
|
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1228 @var{cmdname} @var{arg1} @var{arg2} @dots{} |
| 6638 | 1229 @end example |
| 1230 | |
| 1231 @noindent | |
| 1232 which translates directly to | |
| 1233 | |
| 1234 @example | |
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1235 @var{cmdname} ("@var{arg1}", "@var{arg2}", @dots{}) |
| 6638 | 1236 @end example |
| 1237 | |
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1238 Any regular function can be used as a command if it accepts string input |
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1239 arguments. For example: |
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1240 |
| 6638 | 1241 @example |
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1242 @group |
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1243 toupper lower_case_arg |
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1244 @result{} ans = LOWER_CASE_ARG |
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1245 @end group |
| 6638 | 1246 @end example |
| 1247 | |
| 1248 One difficulty of commands occurs when one of the string input arguments | |
|
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1249 is stored in a variable. Because Octave can't tell the difference between |
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1250 a variable name and an ordinary string, it is not possible to pass a |
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1251 variable as input to a command. In such a situation a command must be |
|
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1252 called as a function. For example: |
| 6549 | 1253 |
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1254 @example |
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1255 @group |
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1256 strvar = "hello world"; |
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1257 toupper strvar |
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1258 @result{} ans = STRVAR |
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1259 toupper (strvar) |
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1260 @result{} ans = HELLO WORLD |
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1261 @end group |
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1262 @end example |
| 6549 | 1263 |
| 1264 | |
| 4167 | 1265 @node Organization of Functions |
| 3294 | 1266 @section Organization of Functions Distributed with Octave |
| 1267 | |
| 1268 Many of Octave's standard functions are distributed as function files. | |
| 1269 They are loosely organized by topic, in subdirectories of | |
| 1270 @file{@var{octave-home}/lib/octave/@var{version}/m}, to make it easier | |
| 1271 to find them. | |
| 1272 | |
| 1273 The following is a list of all the function file subdirectories, and the | |
| 1274 types of functions you will find there. | |
| 1275 | |
| 1276 @table @file | |
| 1277 @item audio | |
| 1278 Functions for playing and recording sounds. | |
| 1279 | |
| 1280 @item control | |
| 1281 Functions for design and simulation of automatic control systems. | |
| 1282 | |
| 1283 @item elfun | |
| 1284 Elementary functions. | |
| 1285 | |
| 6554 | 1286 @item finance |
| 1287 Functions for computing interest payments, investment values, and rates | |
| 1288 of return. | |
| 1289 | |
| 3294 | 1290 @item general |
| 1291 Miscellaneous matrix manipulations, like @code{flipud}, @code{rot90}, | |
| 1292 and @code{triu}, as well as other basic functions, like | |
| 4029 | 1293 @code{ismatrix}, @code{nargchk}, etc. |
| 3294 | 1294 |
| 1295 @item image | |
| 1296 Image processing tools. These functions require the X Window System. | |
| 1297 | |
| 1298 @item io | |
|
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1299 Input-output functions. |
| 3294 | 1300 |
| 1301 @item linear-algebra | |
| 1302 Functions for linear algebra. | |
| 1303 | |
| 1304 @item miscellaneous | |
| 1305 Functions that don't really belong anywhere else. | |
| 1306 | |
| 6554 | 1307 @item optimization |
| 1308 Minimization of functions. | |
| 1309 | |
| 1310 @item path | |
| 1311 Functions to manage the directory path Octave uses to find functions. | |
| 1312 | |
| 1313 @item pkg | |
| 1314 Install external packages of functions in Octave. | |
| 1315 | |
| 3294 | 1316 @item plot |
| 6556 | 1317 Functions for displaying and printing two- and three-dimensional graphs. |
| 3294 | 1318 |
| 1319 @item polynomial | |
| 1320 Functions for manipulating polynomials. | |
| 1321 | |
| 1322 @item set | |
| 1323 Functions for creating and manipulating sets of unique values. | |
| 1324 | |
| 1325 @item signal | |
| 1326 Functions for signal processing applications. | |
| 1327 | |
| 6554 | 1328 @item sparse |
| 1329 Functions for handling sparse matrices. | |
| 1330 | |
| 3294 | 1331 @item specfun |
| 1332 Special functions. | |
| 1333 | |
| 1334 @item special-matrix | |
| 1335 Functions that create special matrix forms. | |
| 1336 | |
| 1337 @item startup | |
| 1338 Octave's system-wide startup file. | |
| 1339 | |
| 1340 @item statistics | |
| 1341 Statistical functions. | |
| 1342 | |
| 1343 @item strings | |
| 1344 Miscellaneous string-handling functions. | |
| 1345 | |
| 6554 | 1346 @item testfun |
| 1347 Perform unit tests on other functions. | |
| 1348 | |
| 3294 | 1349 @item time |
| 1350 Functions related to time keeping. | |
| 1351 @end table |