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1 ## Copyright (C) 2005 Paul Kienzle <pkienzle@users.sf.net> |
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2 ## |
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3 ## This file is part of Octave. |
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4 ## |
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5 ## Octave is free software; you can redistribute it and/or modify it |
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6 ## under the terms of the GNU General Public License as published by |
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7 ## the Free Software Foundation; either version 3 of the License, or (at |
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8 ## your option) any later version. |
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9 ## |
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10 ## Octave is distributed in the hope that it will be useful, but |
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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13 ## General Public License for more details. |
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14 ## |
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15 ## You should have received a copy of the GNU General Public License |
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16 ## along with Octave; see the file COPYING. If not, see |
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17 ## <http://www.gnu.org/licenses/>. |
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18 |
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19 ## -*- texinfo -*- |
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20 ## @deftypefn {Function File} {} fplot (@var{fn}, @var{limits}) |
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21 ## @deftypefnx {Function File} {} fplot (@var{fn}, @var{limits}, @var{tol}) |
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22 ## @deftypefnx {Function File} {} fplot (@var{fn}, @var{limits}, @var{n}) |
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23 ## @deftypefnx {Function File} {} fplot (@dots{}, @var{fmt}) |
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24 ## Plot a function @var{fn}, within the defined limits. @var{fn} |
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25 ## an be either a string, a function handle or an inline function. |
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26 ## The limits of the plot are given by @var{limits} of the form |
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27 ## @code{[@var{xlo}, @var{xhi}]} or @code{[@var{xlo}, @var{xhi}, |
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28 ## @var{ylo}, @var{yhi}]}. @var{tol} is the default tolerance to use for the |
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29 ## plot, and if @var{tol} is an integer it is assumed that it defines the |
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30 ## number points to use in the plot. The @var{fmt} argument is passed |
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31 ## to the plot command. |
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32 ## |
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33 ## @example |
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34 ## fplot ("cos", [0, 2*pi]) |
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35 ## fplot ("[cos(x), sin(x)]", [0, 2*pi]) |
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36 ## @end example |
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37 ## @seealso{plot} |
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38 ## @end deftypefn |
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39 |
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40 function fplot (fn, limits, n, linespec) |
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41 if (nargin < 2 || nargin > 3) |
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42 print_usage (); |
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43 endif |
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44 |
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45 if (nargin < 3) |
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46 n = 0.002; |
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47 endif |
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48 |
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49 have_linespec = true; |
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50 if (nargin < 4) |
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51 have_linespec = false; |
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52 endif |
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53 |
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54 if (ischar (n)) |
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55 have_linespec = true; |
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56 linespec = n; |
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57 n = 0.002; |
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58 endif |
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59 |
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60 if (strcmp (typeinfo (fn), "inline function")) |
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61 fn = vectorize (fn); |
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62 nam = formula (fn); |
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63 elseif (isa (fn, "function_handle")) |
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64 nam = func2str (fn); |
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65 elseif (all (isalnum (fn))) |
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66 nam = fn; |
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67 else |
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68 fn = vectorize (inline (fn)); |
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69 nam = formula (fn); |
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70 endif |
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71 |
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72 if (floor(n) != n) |
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73 tol = n; |
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74 x0 = linspace (limits(1), limits(2), 3)'; |
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75 y0 = feval (fn, x0); |
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76 err0 = Inf; |
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77 n = 5; |
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78 x = linspace (limits(1), limits(2), n)'; |
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79 y = feval (fn, x); |
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80 |
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81 while (n < 2 .^ 20) |
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82 y00 = interp1 (x0, y0, x, "linear"); |
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83 err = 0.5 * max (abs ((y00 - y) ./ (y00 + y))(:)); |
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84 if (err == err0 || 0.5 * max (abs ((y00 - y) ./ (y00 + y))(:)) < tol) |
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85 break; |
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86 endif |
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87 x0 = x; |
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88 y0 = y; |
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89 err0 = err; |
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90 n = 2 * (n - 1) + 1; |
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91 x = linspace (limits(1), limits(2), n)'; |
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92 y = feval (fn, x); |
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93 endwhile |
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94 else |
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95 x = linspace (limits(1), limits(2), n)'; |
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96 y = feval (fn, x); |
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97 endif |
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98 |
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99 if (length (limits) > 2) |
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100 axis (limits); |
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101 endif |
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102 |
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103 if (have_linespec) |
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104 plot (x, y, linespec); |
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105 else |
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106 plot (x, y); |
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107 endif |
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108 if (isvector(y)) |
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109 legend (nam); |
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110 else |
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111 for i=1:columns(y) |
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112 nams{i} = sprintf ("%s(:,%i)", nam, i); |
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113 endfor |
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114 legend (nams{:}); |
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115 endif |
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116 endfunction |
