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annotate doc/interpreter/basics.txi @ 9133:c0cef1436788
Update help text for sections 2.2 and 2.3 of basics.txi
| author | Rik <rdrider0-list@yahoo.com> |
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| date | Fri, 17 Apr 2009 15:16:33 -0700 |
| parents | eb1747dbd360 |
| children | a3739e27b017 |
| rev | line source |
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| 7018 | 1 @c Copyright (C) 1996, 1997, 1999, 2000, 2001, 2002, 2003, 2005, 2006, |
| 8920 | 2 @c 2007, 2008, 2009 John W. Eaton |
| 7018 | 3 @c |
| 4 @c This file is part of Octave. | |
| 5 @c | |
| 6 @c Octave is free software; you can redistribute it and/or modify it | |
| 7 @c under the terms of the GNU General Public License as published by the | |
| 8 @c Free Software Foundation; either version 3 of the License, or (at | |
| 9 @c your option) any later version. | |
| 10 @c | |
| 11 @c Octave is distributed in the hope that it will be useful, but WITHOUT | |
| 12 @c ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 @c FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 @c for more details. | |
| 15 @c | |
| 16 @c You should have received a copy of the GNU General Public License | |
| 17 @c along with Octave; see the file COPYING. If not, see | |
| 18 @c <http://www.gnu.org/licenses/>. | |
| 3294 | 19 |
| 4167 | 20 @node Getting Started |
| 3294 | 21 @chapter Getting Started |
| 22 | |
| 23 This chapter explains some of Octave's basic features, including how to | |
| 24 start an Octave session, get help at the command prompt, edit the | |
| 25 command line, and write Octave programs that can be executed as commands | |
| 26 from your shell. | |
| 27 | |
| 28 @menu | |
| 6620 | 29 * Invoking Octave from the Command Line:: |
| 3294 | 30 * Quitting Octave:: |
| 31 * Getting Help:: | |
| 32 * Command Line Editing:: | |
| 33 * Errors:: | |
| 34 * Executable Octave Programs:: | |
| 35 * Comments:: | |
| 36 @end menu | |
| 37 | |
| 6620 | 38 @node Invoking Octave from the Command Line |
| 39 @section Invoking Octave from the Command Line | |
| 3294 | 40 |
| 41 Normally, Octave is used interactively by running the program | |
| 42 @samp{octave} without any arguments. Once started, Octave reads | |
| 43 commands from the terminal until you tell it to exit. | |
| 44 | |
| 45 You can also specify the name of a file on the command line, and Octave | |
| 46 will read and execute the commands from the named file and then exit | |
| 47 when it is finished. | |
| 48 | |
| 49 You can further control how Octave starts by using the command-line | |
| 50 options described in the next section, and Octave itself can remind you | |
| 51 of the options available. Type @samp{octave --help} to display all | |
| 52 available options and briefly describe their use (@samp{octave -h} is a | |
| 53 shorter equivalent). | |
| 54 | |
| 55 @menu | |
| 56 * Command Line Options:: | |
| 57 * Startup Files:: | |
| 58 @end menu | |
| 59 | |
| 4167 | 60 @node Command Line Options |
| 3294 | 61 @subsection Command Line Options |
| 62 @cindex Octave command options | |
| 63 @cindex command options | |
| 64 @cindex options, Octave command | |
| 65 | |
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66 Here is a complete list of the command line options that Octave |
| 3294 | 67 accepts. |
| 68 | |
| 6620 | 69 |
| 3294 | 70 @table @code |
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71 @item --debug |
| 3294 | 72 @itemx -d |
| 73 @cindex @code{--debug} | |
| 74 @cindex @code{-d} | |
| 75 Enter parser debugging mode. Using this option will cause Octave's | |
| 76 parser to print a lot of information about the commands it reads, and is | |
| 77 probably only useful if you are actually trying to debug the parser. | |
| 78 | |
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79 @item --doc-cache-file @var{filename} |
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80 @cindex @code{--doc-cache-file @var{filename}} |
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81 Specify the name of the doc cache file to use. The value of @var{filename} |
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82 specified on the command line will override any value of |
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83 @w{@code{OCTAVE_DOC_CACHE_FILE}} found in the environment, but not any commands |
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84 in the system or user startup files that use the @code{doc_cache_file} |
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85 function. |
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86 |
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87 @item --echo-commands |
| 3294 | 88 @itemx -x |
| 89 @cindex @code{--echo-commands} | |
| 90 @cindex @code{-x} | |
| 91 Echo commands as they are executed. | |
| 92 | |
| 5190 | 93 @item --eval @var{code} |
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94 Evaluate @var{code} and exit when finished unless @code{--persist} is also |
| 5190 | 95 specified. |
| 96 | |
| 3294 | 97 @item --exec-path @var{path} |
| 98 @cindex @code{--exec-path @var{path}} | |
| 99 Specify the path to search for programs to run. The value of @var{path} | |
| 100 specified on the command line will override any value of | |
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101 @w{@code{OCTAVE_EXEC_PATH}} found in the environment, but not any commands |
| 3294 | 102 in the system or user startup files that set the built-in variable |
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103 @w{@code{EXEC_PATH}}. |
| 3294 | 104 |
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105 @item --help |
| 3294 | 106 @itemx -h |
| 107 @itemx -? | |
| 108 @cindex @code{--help} | |
| 109 @cindex @code{-h} | |
| 110 @cindex @code{-?} | |
| 111 Print short help message and exit. | |
| 112 | |
| 6620 | 113 @item --image-path @var{path} |
| 114 @cindex @code{--image-path @var{path}} | |
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115 Add path to the head of the search path for images. The value of |
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116 @var{path} specified on the command line will override any value of |
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117 @w{@code{OCTAVE_IMAGE_PATH}} found in the environment, but not any commands |
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118 in the system or user startup files that set the built-in variable |
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119 @w{@code{IMAGE_PATH}}. |
| 6620 | 120 |
| 3294 | 121 @item --info-file @var{filename} |
| 122 @cindex @code{--info-file @var{filename}} | |
| 123 Specify the name of the info file to use. The value of @var{filename} | |
| 124 specified on the command line will override any value of | |
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125 @w{@code{OCTAVE_INFO_FILE}} found in the environment, but not any commands |
| 6653 | 126 in the system or user startup files that use the @code{info_file} |
| 6477 | 127 function. |
| 3294 | 128 |
| 129 @item --info-program @var{program} | |
| 130 @cindex @code{--info-program @var{program}} | |
| 131 Specify the name of the info program to use. The value of @var{program} | |
| 132 specified on the command line will override any value of | |
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133 @w{@code{OCTAVE_INFO_PROGRAM}} found in the environment, but not any |
| 6477 | 134 commands in the system or user startup files that use the |
| 135 @code{info_program} function. | |
| 3294 | 136 |
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137 @item --interactive |
| 3294 | 138 @itemx -i |
| 139 @cindex @code{--interactive} | |
| 140 @cindex @code{-i} | |
| 141 Force interactive behavior. This can be useful for running Octave via a | |
| 142 remote shell command or inside an Emacs shell buffer. For another way | |
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143 to run Octave within Emacs, see @ref{Emacs Octave Support}. |
| 3294 | 144 |
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145 @item --line-editing |
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146 @cindex @code{--line-editing} |
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147 Force readline use for command-line editing. |
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148 |
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149 @item --no-history |
| 3428 | 150 @itemx -H |
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151 @cindex @code{--no-history} |
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152 @cindex @code{-H} |
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153 Disable recording of command-line history. |
| 3428 | 154 |
| 3294 | 155 @item --no-init-file |
| 156 @cindex @code{--no-init-file} | |
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157 Don't read the initialization files @file{~/.octaverc} and @file{.octaverc}. |
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158 |
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159 @item --no-init-path |
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160 @cindex @code{--no-init-path} |
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161 Don't initialize the search path for function files to include default |
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162 locations. |
| 3294 | 163 |
| 164 @item --no-line-editing | |
| 165 @cindex @code{--no-line-editing} | |
| 166 Disable command-line editing. | |
| 167 | |
| 168 @item --no-site-file | |
| 169 @cindex @code{--no-site-file} | |
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170 Don't read the site-wide @file{octaverc} initialization files. |
| 3294 | 171 |
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172 @item --norc |
| 3294 | 173 @itemx -f |
| 174 @cindex @code{--norc} | |
| 175 @cindex @code{-f} | |
| 176 Don't read any of the system or user initialization files at startup. | |
| 177 This is equivalent to using both of the options @code{--no-init-file} | |
| 178 and @code{--no-site-file}. | |
| 179 | |
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180 @item --path @var{path} |
| 3294 | 181 @itemx -p @var{path} |
| 182 @cindex @code{--path @var{path}} | |
| 183 @cindex @code{-p @var{path}} | |
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184 Add path to the head of the search path for function files. The |
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185 value of @var{path} specified on the command line will override any value |
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186 of @w{@code{OCTAVE_PATH}} found in the environment, but not any commands in the |
| 6643 | 187 system or user startup files that set the internal load path through one |
| 188 of the path functions. | |
| 3294 | 189 |
| 5190 | 190 @item --persist |
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191 @cindex @code{--persist} |
| 5190 | 192 Go to interactive mode after @code{--eval} or reading from a file |
| 193 named on the command line. | |
| 194 | |
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195 @item --silent |
| 3294 | 196 @itemx --quiet |
| 197 @itemx -q | |
| 198 @cindex @code{--silent} | |
| 199 @cindex @code{--quiet} | |
| 200 @cindex @code{-q} | |
| 201 Don't print the usual greeting and version message at startup. | |
| 202 | |
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203 @item --traditional |
| 3294 | 204 @itemx --braindead |
| 205 @cindex @code{--traditional} | |
| 206 @cindex @code{--braindead} | |
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207 For compatibility with @sc{matlab}, set initial values for |
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208 user preferences to the following values |
| 3294 | 209 |
| 210 @example | |
| 4455 | 211 @group |
| 7031 | 212 PS1 = ">> " |
| 213 PS2 = "" | |
| 214 beep_on_error = true | |
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215 confirm_recursive_rmdir = false |
| 7031 | 216 crash_dumps_octave_core = false |
| 217 default_save_options = "-mat-binary" | |
| 218 fixed_point_format = true | |
| 219 history_timestamp_format_string | |
| 220 = "%%-- %D %I:%M %p --%%" | |
| 221 page_screen_output = false | |
| 222 print_empty_dimensions = false | |
| 6556 | 223 @end group |
| 224 @end example | |
| 225 | |
| 226 @noindent | |
| 227 and disable the following warnings | |
| 228 @example | |
| 229 @group | |
| 7031 | 230 Octave:fopen-file-in-path |
| 231 Octave:function-name-clash | |
| 232 Octave:load-file-in-path | |
| 4455 | 233 @end group |
| 3294 | 234 @end example |
| 235 | |
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236 @item --verbose |
| 3294 | 237 @itemx -V |
| 238 @cindex @code{--verbose} | |
| 239 @cindex @code{-V} | |
| 240 Turn on verbose output. | |
| 241 | |
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242 @item --version |
| 3294 | 243 @itemx -v |
| 244 @cindex @code{--version} | |
| 245 @cindex @code{-v} | |
| 246 Print the program version number and exit. | |
| 247 | |
| 248 @item @var{file} | |
| 5190 | 249 Execute commands from @var{file}. Exit when done unless |
| 250 @code{--persist} is also specified. | |
| 3294 | 251 @end table |
| 252 | |
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253 Octave also includes several functions which return information |
| 3294 | 254 about the command line, including the number of arguments and all of the |
| 255 options. | |
| 256 | |
| 3332 | 257 @DOCSTRING(argv) |
| 3294 | 258 |
| 6550 | 259 @DOCSTRING(program_name) |
| 260 | |
| 3332 | 261 @DOCSTRING(program_invocation_name) |
| 3294 | 262 |
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263 Here is an example of using these functions to reproduce the command |
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264 line which invoked Octave. |
| 3294 | 265 |
| 266 @example | |
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267 @group |
| 6479 | 268 printf ("%s", program_name ()); |
| 6620 | 269 arg_list = argv (); |
| 3294 | 270 for i = 1:nargin |
| 6479 | 271 printf (" %s", arg_list@{i@}); |
| 3294 | 272 endfor |
| 273 printf ("\n"); | |
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274 @end group |
| 3294 | 275 @end example |
| 276 | |
| 277 @noindent | |
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278 @xref{Indexing Cell Arrays}, for an explanation of how to retrieve objects |
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279 from cell arrays, and @ref{Defining Functions}, for information about the |
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280 variable @code{nargin}. |
| 3294 | 281 |
| 4167 | 282 @node Startup Files |
| 3294 | 283 @subsection Startup Files |
| 284 @cindex initialization | |
| 285 @cindex startup | |
| 286 | |
| 6620 | 287 When Octave starts, it looks for commands to execute from the files in |
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288 the following list. These files may contain any valid Octave commands, |
| 6620 | 289 including function definitions. |
| 3294 | 290 |
| 291 @cindex startup files | |
| 292 | |
| 293 @table @code | |
| 294 @item @var{octave-home}/share/octave/site/m/startup/octaverc | |
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295 @cindex site startup file |
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296 where @var{octave-home} is the directory in which Octave is installed |
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297 (the default is @file{@value{OCTAVEHOME}}). |
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298 This file is provided so that changes to the default Octave environment |
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299 can be made globally for all users at your site for all versions of Octave |
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300 you have installed. Care should be taken when making changes to this file |
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301 since all users of Octave at your site will be affected. The default file |
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302 may be overridden by the environment variable @w{@code{OCTAVE_SITE_INITFILE}}. |
| 3294 | 303 |
| 304 @item @var{octave-home}/share/octave/@var{version}/m/startup/octaverc | |
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305 @cindex version startup file |
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306 where @var{octave-home} is the directory in which Octave is |
| 3294 | 307 installed (the default is @file{@value{OCTAVEHOME}}), and @var{version} |
| 308 is the version number of Octave. This file is provided so that changes | |
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309 to the default Octave environment can be made globally for all users of |
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310 a particular version of Octave. Care should be taken when making |
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311 changes to this file since all users of Octave at your site will be |
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312 affected. The default file may be overridden by the environment variable |
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313 @w{@code{OCTAVE_VERSION_INITFILE}}. |
| 3294 | 314 |
| 315 @item ~/.octaverc | |
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316 @cindex personal startup file |
| 3294 | 317 @cindex @code{~/.octaverc} |
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318 This file is used to make personal changes to the default |
| 3294 | 319 Octave environment. |
| 320 | |
| 321 @item .octaverc | |
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322 @cindex project startup file |
| 3294 | 323 @cindex @code{.octaverc} |
| 324 This file can be used to make changes to the default Octave environment | |
| 325 for a particular project. Octave searches for this file in the current | |
| 326 directory after it reads @file{~/.octaverc}. Any use of the @code{cd} | |
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327 command in the @file{~/.octaverc} file will affect the directory where |
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328 Octave searches for @file{.octaverc}. |
| 3294 | 329 |
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330 If you start Octave in your home directory, commands from the file |
| 3294 | 331 @file{~/.octaverc} will only be executed once. |
| 332 @end table | |
| 333 | |
| 334 A message will be displayed as each of the startup files is read if you | |
| 335 invoke Octave with the @code{--verbose} option but without the | |
| 336 @code{--silent} option. | |
| 337 | |
| 4167 | 338 @node Quitting Octave |
| 3294 | 339 @section Quitting Octave |
| 340 @cindex exiting octave | |
| 341 @cindex quitting octave | |
| 342 | |
| 3332 | 343 @DOCSTRING(quit) |
| 3294 | 344 |
| 3332 | 345 @DOCSTRING(atexit) |
| 3294 | 346 |
| 4167 | 347 @node Getting Help |
| 3294 | 348 @section Commands for Getting Help |
| 349 @cindex on-line help | |
| 350 @cindex help, on-line | |
| 351 | |
| 352 The entire text of this manual is available from the Octave prompt | |
| 6620 | 353 via the command @kbd{doc}. In addition, the documentation for |
| 3294 | 354 individual user-written functions and variables is also available via |
| 355 the @kbd{help} command. This section describes the commands used for | |
| 356 reading the manual and the documentation strings for user-supplied | |
| 357 functions and variables. @xref{Function Files}, for more information | |
| 358 about how to document the functions you write. | |
| 359 | |
| 3332 | 360 @DOCSTRING(help) |
| 3294 | 361 |
| 6549 | 362 @DOCSTRING(doc) |
| 363 | |
| 364 @DOCSTRING(lookfor) | |
| 365 | |
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366 To see what is new in the current release of Octave, use the @code{news} |
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367 function. |
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368 |
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369 @DOCSTRING(news) |
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370 |
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371 @DOCSTRING(info) |
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372 |
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373 @DOCSTRING(warranty) |
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374 |
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375 The following functions can be used to change which programs are used |
| 6620 | 376 for displaying the documentation, and where the documentation can be |
| 377 found. | |
| 3294 | 378 |
| 6477 | 379 @DOCSTRING(info_file) |
| 3294 | 380 |
| 6477 | 381 @DOCSTRING(info_program) |
| 3294 | 382 |
| 6477 | 383 @DOCSTRING(makeinfo_program) |
| 3686 | 384 |
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385 @DOCSTRING(doc_cache_file) |
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386 |
| 3332 | 387 @DOCSTRING(suppress_verbose_help_message) |
| 3294 | 388 |
| 4167 | 389 @node Command Line Editing |
| 3294 | 390 @section Command Line Editing |
| 391 @cindex command-line editing | |
| 392 @cindex editing the command line | |
| 393 | |
| 394 Octave uses the GNU readline library to provide an extensive set of | |
| 395 command-line editing and history features. Only the most common | |
| 396 features are described in this manual. Please see The GNU Readline | |
| 397 Library manual for more information. | |
| 398 | |
| 399 To insert printing characters (letters, digits, symbols, etc.), simply | |
| 400 type the character. Octave will insert the character at the cursor and | |
| 401 advance the cursor forward. | |
| 402 | |
| 403 Many of the command-line editing functions operate using control | |
| 404 characters. For example, the character @kbd{Control-a} moves the cursor | |
| 405 to the beginning of the line. To type @kbd{C-a}, hold down @key{CTRL} | |
| 406 and then press @key{a}. In the following sections, control characters | |
| 407 such as @kbd{Control-a} are written as @kbd{C-a}. | |
| 408 | |
| 409 Another set of command-line editing functions use Meta characters. On | |
| 410 some terminals, you type @kbd{M-u} by holding down @key{META} and | |
| 411 pressing @key{u}. If your terminal does not have a @key{META} key, you | |
| 7001 | 412 can still type Meta characters using two-character sequences starting |
| 3294 | 413 with @kbd{ESC}. Thus, to enter @kbd{M-u}, you could type |
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414 @key{ESC} @key{u}. The @kbd{ESC} character sequences are also allowed on |
| 3294 | 415 terminals with real Meta keys. In the following sections, Meta |
| 416 characters such as @kbd{Meta-u} are written as @kbd{M-u}. | |
| 417 | |
| 3428 | 418 |
| 3294 | 419 @menu |
| 420 * Cursor Motion:: | |
| 421 * Killing and Yanking:: | |
| 422 * Commands For Text:: | |
| 423 * Commands For Completion:: | |
| 424 * Commands For History:: | |
| 3439 | 425 * Customizing readline:: |
| 3294 | 426 * Customizing the Prompt:: |
| 427 * Diary and Echo Commands:: | |
| 428 @end menu | |
| 429 | |
| 4167 | 430 @node Cursor Motion |
| 3294 | 431 @subsection Cursor Motion |
| 432 | |
| 433 The following commands allow you to position the cursor. | |
| 434 | |
| 435 @table @kbd | |
| 436 @item C-b | |
| 437 Move back one character. | |
| 438 | |
| 439 @item C-f | |
| 440 Move forward one character. | |
| 441 | |
| 442 @item @key{DEL} | |
| 443 Delete the character to the left of the cursor. | |
| 444 | |
| 445 @item C-d | |
| 446 Delete the character underneath the cursor. | |
| 447 | |
| 448 @item M-f | |
| 449 Move forward a word. | |
| 450 | |
| 451 @item M-b | |
| 452 Move backward a word. | |
| 453 | |
| 454 @item C-a | |
| 455 Move to the start of the line. | |
| 456 | |
| 457 @item C-e | |
| 458 Move to the end of the line. | |
| 459 | |
| 460 @item C-l | |
| 461 Clear the screen, reprinting the current line at the top. | |
| 462 | |
| 463 @item C-_ | |
| 464 @itemx C-/ | |
| 465 Undo the last thing that you did. You can undo all the way back to an | |
| 466 empty line. | |
| 467 | |
| 468 @item M-r | |
| 469 Undo all changes made to this line. This is like typing the `undo' | |
| 470 command enough times to get back to the beginning. | |
| 471 @end table | |
| 472 | |
| 473 The above table describes the most basic possible keystrokes that you need | |
| 474 in order to do editing of the input line. On most terminals, you can | |
| 475 also use the arrow keys in place of @kbd{C-f} and @kbd{C-b} to move | |
| 476 forward and backward. | |
| 477 | |
| 478 Notice how @kbd{C-f} moves forward a character, while @kbd{M-f} moves | |
| 479 forward a word. It is a loose convention that control keystrokes | |
| 480 operate on characters while meta keystrokes operate on words. | |
| 481 | |
| 482 @cindex clearing the screen | |
| 483 | |
| 6620 | 484 The function @code{clc} will allow you to clear the screen from within |
| 485 Octave programs. | |
| 486 | |
| 487 @ifinfo | |
| 3332 | 488 @DOCSTRING(clc) |
| 6620 | 489 @end ifinfo |
| 3294 | 490 |
| 4167 | 491 @node Killing and Yanking |
| 3294 | 492 @subsection Killing and Yanking |
| 493 | |
| 494 @dfn{Killing} text means to delete the text from the line, but to save | |
| 495 it away for later use, usually by @dfn{yanking} it back into the line. | |
| 496 If the description for a command says that it `kills' text, then you can | |
| 497 be sure that you can get the text back in a different (or the same) | |
| 498 place later. | |
| 499 | |
| 500 Here is the list of commands for killing text. | |
| 501 | |
| 502 @table @kbd | |
| 503 @item C-k | |
| 504 Kill the text from the current cursor position to the end of the line. | |
| 505 | |
| 506 @item M-d | |
| 507 Kill from the cursor to the end of the current word, or if between | |
| 508 words, to the end of the next word. | |
| 509 | |
| 510 @item M-@key{DEL} | |
| 511 Kill from the cursor to the start of the previous word, or if between | |
| 512 words, to the start of the previous word. | |
| 513 | |
| 514 @item C-w | |
| 515 Kill from the cursor to the previous whitespace. This is different than | |
| 516 @kbd{M-@key{DEL}} because the word boundaries differ. | |
| 517 @end table | |
| 518 | |
| 519 And, here is how to @dfn{yank} the text back into the line. Yanking | |
| 520 means to copy the most-recently-killed text from the kill buffer. | |
| 521 | |
| 522 @table @kbd | |
| 523 @item C-y | |
| 524 Yank the most recently killed text back into the buffer at the cursor. | |
| 525 | |
| 526 @item M-y | |
| 527 Rotate the kill-ring, and yank the new top. You can only do this if | |
| 528 the prior command is @kbd{C-y} or @kbd{M-y}. | |
| 529 @end table | |
| 530 | |
| 531 When you use a kill command, the text is saved in a @dfn{kill-ring}. | |
| 532 Any number of consecutive kills save all of the killed text together, so | |
| 533 that when you yank it back, you get it in one clean sweep. The kill | |
| 534 ring is not line specific; the text that you killed on a previously | |
| 535 typed line is available to be yanked back later, when you are typing | |
| 536 another line. | |
| 537 | |
| 4167 | 538 @node Commands For Text |
| 3294 | 539 @subsection Commands For Changing Text |
| 540 | |
| 541 The following commands can be used for entering characters that would | |
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542 otherwise have a special meaning (e.g., @key{TAB}, @kbd{C-q}, etc.), or |
| 3294 | 543 for quickly correcting typing mistakes. |
| 544 | |
| 545 @table @kbd | |
| 546 @item C-q | |
| 547 @itemx C-v | |
| 548 Add the next character that you type to the line verbatim. This is | |
| 549 how to insert things like @kbd{C-q} for example. | |
| 550 | |
| 551 @item M-@key{TAB} | |
| 552 Insert a tab character. | |
| 553 | |
| 554 @item C-t | |
| 555 Drag the character before the cursor forward over the character at the | |
| 556 cursor, also moving the cursor forward. If the cursor is at the end of | |
| 557 the line, then transpose the two characters before it. | |
| 558 | |
| 559 @item M-t | |
| 560 Drag the word behind the cursor past the word in front of the cursor | |
| 561 moving the cursor over that word as well. | |
| 562 | |
| 563 @item M-u | |
| 564 Uppercase the characters following the cursor to the end of the current | |
| 565 (or following) word, moving the cursor to the end of the word. | |
| 566 | |
| 567 @item M-l | |
| 6620 | 568 Lowercase the characters following the cursor to the end of the current |
| 3294 | 569 (or following) word, moving the cursor to the end of the word. |
| 570 | |
| 571 @item M-c | |
| 572 Uppercase the character following the cursor (or the beginning of the | |
| 573 next word if the cursor is between words), moving the cursor to the end | |
| 574 of the word. | |
| 575 @end table | |
| 576 | |
| 4167 | 577 @node Commands For Completion |
| 3294 | 578 @subsection Letting Readline Type For You |
| 579 @cindex command completion | |
| 580 | |
| 581 The following commands allow Octave to complete command and variable | |
| 582 names for you. | |
| 583 | |
| 584 @table @kbd | |
| 585 @item @key{TAB} | |
| 586 Attempt to do completion on the text before the cursor. Octave can | |
| 587 complete the names of commands and variables. | |
| 588 | |
| 589 @item M-? | |
| 590 List the possible completions of the text before the cursor. | |
| 591 @end table | |
| 592 | |
| 3332 | 593 @DOCSTRING(completion_append_char) |
| 3294 | 594 |
| 3332 | 595 @DOCSTRING(completion_matches) |
| 3294 | 596 |
| 4167 | 597 @node Commands For History |
| 3294 | 598 @subsection Commands For Manipulating The History |
| 599 @cindex command history | |
| 600 @cindex input history | |
| 601 @cindex history of commands | |
| 602 | |
| 603 Octave normally keeps track of the commands you type so that you can | |
| 604 recall previous commands to edit or execute them again. When you exit | |
| 605 Octave, the most recent commands you have typed, up to the number | |
| 606 specified by the variable @code{history_size}, are saved in a file. | |
| 607 When Octave starts, it loads an initial list of commands from the file | |
| 608 named by the variable @code{history_file}. | |
| 609 | |
| 610 Here are the commands for simple browsing and searching the history | |
| 611 list. | |
| 612 | |
| 613 @table @kbd | |
| 614 @item @key{LFD} | |
| 615 @itemx @key{RET} | |
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616 Accept the current line regardless of where the cursor is. If the line is |
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617 non-empty, add it to the history list. If the line was a history |
| 3294 | 618 line, then restore the history line to its original state. |
| 619 | |
| 620 @item C-p | |
| 621 Move `up' through the history list. | |
| 622 | |
| 623 @item C-n | |
| 624 Move `down' through the history list. | |
| 625 | |
| 626 @item M-< | |
| 627 Move to the first line in the history. | |
| 628 | |
| 629 @item M-> | |
| 630 Move to the end of the input history, i.e., the line you are entering! | |
| 631 | |
| 632 @item C-r | |
| 633 Search backward starting at the current line and moving `up' through | |
| 634 the history as necessary. This is an incremental search. | |
| 635 | |
| 636 @item C-s | |
| 637 Search forward starting at the current line and moving `down' through | |
| 638 the history as necessary. | |
| 639 @end table | |
| 640 | |
| 641 On most terminals, you can also use the arrow keys in place of @kbd{C-p} | |
| 642 and @kbd{C-n} to move through the history list. | |
| 643 | |
| 644 In addition to the keyboard commands for moving through the history | |
| 645 list, Octave provides three functions for viewing, editing, and | |
| 646 re-running chunks of commands from the history list. | |
| 647 | |
| 3332 | 648 @DOCSTRING(history) |
| 3294 | 649 |
| 3332 | 650 @DOCSTRING(edit_history) |
| 3294 | 651 |
| 3332 | 652 @DOCSTRING(run_history) |
| 3294 | 653 |
| 6620 | 654 Octave also allows you customize the details of how and where the history |
| 655 is saved. | |
| 3294 | 656 |
| 3332 | 657 @DOCSTRING(history_file) |
| 3294 | 658 |
| 3332 | 659 @DOCSTRING(history_size) |
| 3294 | 660 |
| 3332 | 661 @DOCSTRING(saving_history) |
| 3294 | 662 |
| 6550 | 663 @DOCSTRING(history_timestamp_format_string) |
| 664 | |
| 6620 | 665 @DOCSTRING(EDITOR) |
| 666 | |
| 4167 | 667 @node Customizing readline |
| 3428 | 668 @subsection Customizing @code{readline} |
| 669 | |
| 6620 | 670 As mentioned earlier Octave uses the GNU readline library for |
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671 command-line editing and history features. It is possible to |
| 6620 | 672 customize how readline works through a configuration file. |
| 673 | |
| 5775 | 674 @c FIXME -- need a brief description of the ~/.inputrc file here. |
| 3428 | 675 |
| 3439 | 676 @DOCSTRING(read_readline_init_file) |
| 3428 | 677 |
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678 @DOCSTRING(re_read_readline_init_file) |
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679 |
| 4167 | 680 @node Customizing the Prompt |
| 3294 | 681 @subsection Customizing the Prompt |
| 682 @cindex prompt customization | |
| 683 @cindex customizing the prompt | |
| 684 | |
| 685 The following variables are available for customizing the appearance of | |
| 686 the command-line prompts. Octave allows the prompt to be customized by | |
| 687 inserting a number of backslash-escaped special characters that are | |
| 688 decoded as follows: | |
| 689 | |
| 690 @table @samp | |
| 691 @item \t | |
| 692 The time. | |
| 693 | |
| 694 @item \d | |
| 695 The date. | |
| 696 | |
| 697 @item \n | |
| 698 Begins a new line by printing the equivalent of a carriage return | |
| 699 followed by a line feed. | |
| 700 | |
| 701 @item \s | |
| 702 The name of the program (usually just @samp{octave}). | |
| 703 | |
| 704 @item \w | |
| 705 The current working directory. | |
| 706 | |
| 707 @item \W | |
| 708 The basename of the current working directory. | |
| 709 | |
| 710 @item \u | |
| 711 The username of the current user. | |
| 712 | |
| 713 @item \h | |
| 714 The hostname, up to the first `.'. | |
| 715 | |
| 716 @item \H | |
| 717 The hostname. | |
| 718 | |
| 719 @item \# | |
| 720 The command number of this command, counting from when Octave starts. | |
| 721 | |
| 722 @item \! | |
| 723 The history number of this command. This differs from @samp{\#} by the | |
| 724 number of commands in the history list when Octave starts. | |
| 725 | |
| 726 @item \$ | |
| 727 If the effective UID is 0, a @samp{#}, otherwise a @samp{$}. | |
| 728 | |
| 729 @item \nnn | |
| 730 The character whose character code in octal is @var{nnn}. | |
| 731 | |
| 732 @item \\ | |
| 733 A backslash. | |
| 734 @end table | |
| 735 | |
| 3332 | 736 @DOCSTRING(PS1) |
| 3294 | 737 |
| 3332 | 738 @DOCSTRING(PS2) |
| 3294 | 739 |
| 3332 | 740 @DOCSTRING(PS4) |
| 3294 | 741 |
| 4167 | 742 @node Diary and Echo Commands |
| 3294 | 743 @subsection Diary and Echo Commands |
| 744 @cindex diary of commands and output | |
| 6939 | 745 @cindex command and output logs |
| 3294 | 746 @cindex logging commands and output |
| 747 @cindex echoing executing commands | |
| 748 @cindex command echoing | |
| 749 | |
| 750 Octave's diary feature allows you to keep a log of all or part of an | |
| 751 interactive session by recording the input you type and the output that | |
| 752 Octave produces in a separate file. | |
| 753 | |
| 3332 | 754 @DOCSTRING(diary) |
| 3294 | 755 |
| 756 Sometimes it is useful to see the commands in a function or script as | |
| 757 they are being evaluated. This can be especially helpful for debugging | |
| 758 some kinds of problems. | |
| 759 | |
| 3332 | 760 @DOCSTRING(echo) |
| 3294 | 761 |
| 3332 | 762 @DOCSTRING(echo_executing_commands) |
| 3294 | 763 |
| 4167 | 764 @node Errors |
| 3294 | 765 @section How Octave Reports Errors |
| 766 @cindex error messages | |
| 767 @cindex messages, error | |
| 768 | |
| 769 Octave reports two kinds of errors for invalid programs. | |
| 770 | |
| 771 A @dfn{parse error} occurs if Octave cannot understand something you | |
| 772 have typed. For example, if you misspell a keyword, | |
| 773 | |
| 774 @example | |
| 775 octave:13> functon y = f (x) y = x^2; endfunction | |
| 776 @end example | |
| 777 | |
| 778 @noindent | |
| 779 Octave will respond immediately with a message like this: | |
| 780 | |
| 781 @example | |
|
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782 @group |
| 3294 | 783 parse error: |
| 784 | |
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785 syntax error |
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786 |
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787 >>> functon y = f (x) y = x^2; endfunction |
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788 ^ |
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789 @end group |
| 3294 | 790 @end example |
| 791 | |
| 792 @noindent | |
| 793 For most parse errors, Octave uses a caret (@samp{^}) to mark the point | |
| 794 on the line where it was unable to make sense of your input. In this | |
| 795 case, Octave generated an error message because the keyword | |
| 796 @code{function} was misspelled. Instead of seeing @samp{function f}, | |
| 797 Octave saw two consecutive variable names, which is invalid in this | |
| 798 context. It marked the error at @code{y} because the first name by | |
| 799 itself was accepted as valid input. | |
| 800 | |
| 801 Another class of error message occurs at evaluation time. These | |
| 802 errors are called @dfn{run-time errors}, or sometimes | |
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803 @dfn{evaluation errors}, because they occur when your program is being |
| 3294 | 804 @dfn{run}, or @dfn{evaluated}. For example, if after correcting the |
| 805 mistake in the previous function definition, you type | |
| 806 | |
| 807 @example | |
| 808 octave:13> f () | |
| 809 @end example | |
| 810 | |
| 811 @noindent | |
| 812 Octave will respond with | |
| 813 | |
| 7031 | 814 @c Using 'smallexample' to make text fit on page when creating smallbook. |
| 815 @smallexample | |
| 3294 | 816 @group |
| 817 error: `x' undefined near line 1 column 24 | |
|
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818 error: called from: |
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819 error: f at line 1, column 22 |
| 3294 | 820 @end group |
| 7031 | 821 @end smallexample |
| 3294 | 822 |
| 6620 | 823 @noindent |
| 3294 | 824 This error message has several parts, and gives you quite a bit of |
| 825 information to help you locate the source of the error. The messages | |
| 826 are generated from the point of the innermost error, and provide a | |
| 827 traceback of enclosing expressions and function calls. | |
| 828 | |
| 829 In the example above, the first line indicates that a variable named | |
| 830 @samp{x} was found to be undefined near line 1 and column 24 of some | |
| 831 function or expression. For errors occurring within functions, lines | |
| 832 are counted from the beginning of the file containing the function | |
| 833 definition. For errors occurring at the top level, the line number | |
| 834 indicates the input line number, which is usually displayed in the | |
| 835 prompt string. | |
| 836 | |
|
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837 The second and third lines in the error message indicates that the error occurred |
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838 within the function @code{f}. If the function @code{f} had been called from |
|
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839 another function, for example, @code{g}, the list of errors would have ended with |
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840 one more line: |
| 3294 | 841 |
| 842 @example | |
|
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843 error: g at line 1, column 17 |
| 3294 | 844 @end example |
| 845 | |
|
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846 These lists of function calls make it fairly easy to trace the |
| 3294 | 847 path your program took before the error occurred, and to correct the |
| 848 error before trying again. | |
| 849 | |
| 4167 | 850 @node Executable Octave Programs |
| 3294 | 851 @section Executable Octave Programs |
| 852 @cindex executable scripts | |
| 853 @cindex scripts | |
| 854 @cindex self contained programs | |
| 855 @cindex program, self contained | |
| 856 @cindex @samp{#!} | |
| 857 | |
| 858 Once you have learned Octave, you may want to write self-contained | |
| 859 Octave scripts, using the @samp{#!} script mechanism. You can do this | |
| 860 on GNU systems and on many Unix systems @footnote{The @samp{#!} | |
| 861 mechanism works on Unix systems derived from Berkeley Unix, System V | |
| 6481 | 862 Release 4, and some System V Release 3 systems.}. |
| 863 | |
| 864 Self-contained Octave scripts are useful when you want to write a | |
| 865 program which users can invoke without knowing that the program is | |
| 866 written in the Octave language. | |
| 3294 | 867 |
| 868 For example, you could create a text file named @file{hello}, containing | |
| 869 the following lines: | |
| 870 | |
| 871 @example | |
| 872 @group | |
| 873 #! @var{octave-interpreter-name} -qf | |
| 874 # a sample Octave program | |
| 875 printf ("Hello, world!\n"); | |
| 876 @end group | |
| 877 @end example | |
| 878 | |
| 879 @noindent | |
| 880 (where @var{octave-interpreter-name} should be replaced with the full | |
| 6481 | 881 file name for your Octave binary). Note that this will only work if |
|
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882 @samp{#!} appears at the very beginning of the file. After making this |
| 6481 | 883 file executable |
| 3294 | 884 (with the @code{chmod} command), you can simply type: |
| 885 | |
| 886 @example | |
| 887 hello | |
| 888 @end example | |
| 889 | |
| 890 @noindent | |
| 891 at the shell, and the system will arrange to run Octave as if you had | |
| 892 typed: | |
| 893 | |
| 894 @example | |
| 895 octave hello | |
| 896 @end example | |
| 897 | |
| 898 The line beginning with @samp{#!} lists the full file name of an | |
| 899 interpreter to be run, and an optional initial command line argument to | |
| 900 pass to that interpreter. The operating system then runs the | |
| 901 interpreter with the given argument and the full argument list of the | |
| 902 executed program. The first argument in the list is the full file name | |
|
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903 of the Octave program. The rest of the argument list will either be |
| 3294 | 904 options to Octave, or data files, or both. The @samp{-qf} option is |
| 905 usually specified in stand-alone Octave programs to prevent them from | |
| 906 printing the normal startup message, and to keep them from behaving | |
| 907 differently depending on the contents of a particular user's | |
| 6620 | 908 @file{~/.octaverc} file. @xref{Invoking Octave from the Command Line}. |
| 6481 | 909 |
| 910 Note that some operating systems may place a limit on the number of | |
| 911 characters that are recognized after @samp{#!}. Also, the various | |
| 912 shells/systems parse differently the arguments appearing in a @samp{#!} | |
| 913 line. The majority of them group together all the arguments in a string | |
| 6939 | 914 and pass it to the interpreter as a single argument. In this case, the |
| 6481 | 915 following script: |
| 916 | |
| 917 @example | |
| 918 @group | |
| 919 #! @var{octave-interpreter-name} -q -f # comment | |
| 920 @end group | |
| 921 @end example | |
| 922 | |
| 923 @noindent | |
| 924 is equivalent to type at the command line: | |
| 3294 | 925 |
| 6481 | 926 @example |
| 927 @group | |
| 928 octave "-q -f # comment" | |
| 929 @end group | |
| 930 @end example | |
| 3294 | 931 |
| 6481 | 932 @noindent |
| 933 which would obviously produce an error message. Unfortunately, it is | |
| 934 impossible for Octave to know whether it has been called from the command | |
| 935 line or from a @samp{#!} script, so some care is needed when using the | |
| 936 @samp{#!} mechanism. | |
| 937 | |
| 938 Note that when Octave is started from an executable script, the built-in | |
| 939 function @code{argv} returns a cell array containing the command line | |
| 940 arguments passed to an executable Octave script, not the arguments | |
| 941 passed to the Octave interpreter on the @samp{#!} line of the script. | |
| 942 For example, the following program will reproduce the command line that | |
| 943 is used to execute script, not @samp{-qf}. | |
| 3294 | 944 |
| 945 @example | |
| 946 @group | |
| 947 #! /bin/octave -qf | |
| 6479 | 948 printf ("%s", program_name ()); |
| 6620 | 949 arg_list = argv (); |
| 3294 | 950 for i = 1:nargin |
| 6479 | 951 printf (" %s", arg_list@{i@}); |
| 3294 | 952 endfor |
| 953 printf ("\n"); | |
| 954 @end group | |
| 955 @end example | |
| 956 | |
| 4167 | 957 @node Comments |
| 3294 | 958 @section Comments in Octave Programs |
| 959 @cindex comments | |
| 960 @cindex use of comments | |
| 961 @cindex documenting Octave programs | |
| 962 @cindex programs | |
| 963 | |
| 964 A @dfn{comment} is some text that is included in a program for the sake | |
|
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965 of human readers, and that is not an executable part of the program. |
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966 Comments can explain what the program does, and how it works. Nearly all |
| 3294 | 967 programming languages have provisions for comments, because programs are |
| 968 typically hard to understand without them. | |
| 969 | |
|
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970 @menu |
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971 * Single Line Comments:: |
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972 * Block Comments:: |
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973 * Comments and the Help System:: |
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974 @end menu |
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975 |
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976 @node Single Line Comments |
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977 @subsection Single Line Comments |
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978 @cindex @samp{#} |
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979 @cindex @samp{%} |
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980 |
| 3294 | 981 In the Octave language, a comment starts with either the sharp sign |
| 982 character, @samp{#}, or the percent symbol @samp{%} and continues to the | |
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983 end of the line. Any text following the sharp sign or percent symbol is |
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984 ignored by the Octave interpreter and not executed. The following example |
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985 shows whole line and partial line comments. |
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986 @example |
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987 @group |
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988 function countdown |
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989 # Count down for main rocket engines |
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990 disp(3); |
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991 disp(2); |
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992 disp(1); |
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993 disp("Blast Off!"); # Rocket leaves pad |
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994 endfunction |
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995 @end group |
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996 @end example |
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997 |
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998 @node Block Comments |
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999 @subsection Block Comments |
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1000 @cindex multi-line comments |
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1001 @cindex @samp{#@{} |
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1002 @cindex @samp{%@{} |
| 3294 | 1003 |
|
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1004 Entire blocks of code can be commented by enclosing the code between |
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1005 matching @samp{#@{} and @samp{#@}} or @samp{%@{} and @samp{%@}} markers. |
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1006 For example, |
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1007 @example |
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1008 @group |
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1009 function quick_countdown |
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1010 # Count down for main rocket engines |
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1011 disp(3); |
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1012 #@{ |
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1013 disp(2); |
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1014 disp(1); |
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1015 #@} |
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1016 disp("Blast Off!"); # Rocket leaves pad |
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1017 endfunction |
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1018 @end group |
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1019 @end example |
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1020 |
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1021 @noindent |
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1022 will produce a very quick countdown from '3' to 'Blast Off' as the |
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1023 lines "@code{disp(2);}" and "@code{disp(3);}" won't be executed. |
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1024 |
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1025 @node Comments and the Help System |
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1026 @subsection Comments and the Help System |
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1027 @cindex documenting functions |
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1028 @cindex documenting user scripts |
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1029 @cindex help, user-defined functions |
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Documentation cleanup of basics.texi
Rik <rdrider0-list@yahoo.com>
parents:
9032
diff
changeset
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1030 |
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57649dcecb55
Documentation cleanup of basics.texi
Rik <rdrider0-list@yahoo.com>
parents:
9032
diff
changeset
|
1031 The @code{help} command (@pxref{Getting Help}) is able to find the first |
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57649dcecb55
Documentation cleanup of basics.texi
Rik <rdrider0-list@yahoo.com>
parents:
9032
diff
changeset
|
1032 block of comments in a function (even those that are composed directly |
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57649dcecb55
Documentation cleanup of basics.texi
Rik <rdrider0-list@yahoo.com>
parents:
9032
diff
changeset
|
1033 on the command line). This means that the same commands used to get help |
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57649dcecb55
Documentation cleanup of basics.texi
Rik <rdrider0-list@yahoo.com>
parents:
9032
diff
changeset
|
1034 on built-in functions are available for user-defined functions. For |
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57649dcecb55
Documentation cleanup of basics.texi
Rik <rdrider0-list@yahoo.com>
parents:
9032
diff
changeset
|
1035 example, after defining the function @code{f} below, |
| 3294 | 1036 @example |
| 1037 @group | |
| 1038 function xdot = f (x, t) | |
| 1039 | |
| 1040 # usage: f (x, t) | |
| 1041 # | |
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9035
57649dcecb55
Documentation cleanup of basics.texi
Rik <rdrider0-list@yahoo.com>
parents:
9032
diff
changeset
|
1042 # This function defines the right-hand |
| 3294 | 1043 # side functions for a set of nonlinear |
| 1044 # differential equations. | |
| 1045 | |
| 1046 r = 0.25; | |
| 1047 @dots{} | |
| 1048 endfunction | |
| 1049 @end group | |
| 1050 @end example | |
| 1051 | |
| 1052 the command @kbd{help f} produces the output | |
| 1053 | |
| 1054 @example | |
| 1055 @group | |
| 1056 usage: f (x, t) | |
| 1057 | |
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9035
57649dcecb55
Documentation cleanup of basics.texi
Rik <rdrider0-list@yahoo.com>
parents:
9032
diff
changeset
|
1058 This function defines the right-hand |
| 3294 | 1059 side functions for a set of nonlinear |
| 1060 differential equations. | |
| 1061 @end group | |
| 1062 @end example | |
| 1063 | |
| 1064 Although it is possible to put comment lines into keyboard-composed | |
| 1065 throw-away Octave programs, it usually isn't very useful, because the | |
| 1066 purpose of a comment is to help you or another person understand the | |
| 1067 program at a later time. | |
| 1068 | |
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9035
57649dcecb55
Documentation cleanup of basics.texi
Rik <rdrider0-list@yahoo.com>
parents:
9032
diff
changeset
|
1069 The @code{help} parser currently only recognizes single line comments |
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57649dcecb55
Documentation cleanup of basics.texi
Rik <rdrider0-list@yahoo.com>
parents:
9032
diff
changeset
|
1070 (@pxref{Single Line Comments}) and not block comments for the initial |
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57649dcecb55
Documentation cleanup of basics.texi
Rik <rdrider0-list@yahoo.com>
parents:
9032
diff
changeset
|
1071 help text. |