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maint: Update copyright notices for 2016.
author John W. Eaton <jwe@octave.org>
date Wed, 17 Aug 2016 01:05:19 -0400
parents ffad2baa90f7
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1 ## Copyright (C) 2012-2016 Jordi Gutiérrez Hermoso
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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 {} {} nthargout (@var{n}, @var{func}, @dots{})
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21 ## @deftypefnx {} {} nthargout (@var{n}, @var{ntot}, @var{func}, @dots{})
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22 ## Return the @var{n}th output argument of the function specified by the
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23 ## function handle or string @var{func}.
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24 ##
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25 ## Any additional arguments are passed directly to @var{func}. The total
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26 ## number of arguments to call @var{func} with can be passed in @var{ntot}; by
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27 ## default @var{ntot} is @var{n}. The input @var{n} can also be a vector of
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28 ## indices of the output, in which case the output will be a cell array of the
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29 ## requested output arguments.
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30 ##
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31 ## The intended use @code{nthargout} is to avoid intermediate variables. For
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32 ## example, when finding the indices of the maximum entry of a matrix, the
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33 ## following two compositions of nthargout
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34 ##
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35 ## @example
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36 ## @group
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37 ## @var{m} = magic (5);
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38 ## cell2mat (nthargout ([1, 2], @@ind2sub, size (@var{m}),
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39 ## nthargout (2, @@max, @var{m}(:))))
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40 ## @result{} 5 3
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41 ## @end group
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42 ## @end example
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43 ##
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44 ## @noindent
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45 ## are completely equivalent to the following lines:
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46 ##
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47 ## @example
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48 ## @group
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49 ## @var{m} = magic (5);
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50 ## [~, idx] = max (@var{M}(:));
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51 ## [i, j] = ind2sub (size (@var{m}), idx);
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52 ## [i, j]
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53 ## @result{} 5 3
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54 ## @end group
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55 ## @end example
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56 ##
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57 ## It can also be helpful to have all output arguments in a single cell in the
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58 ## following manner:
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59 ##
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60 ## @example
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61 ## @var{USV} = nthargout ([1:3], @@svd, hilb (5));
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62 ## @end example
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63 ##
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64 ## @seealso{nargin, nargout, varargin, varargout, isargout}
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65 ## @end deftypefn
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66
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67 ## Author: Jordi Gutiérrez Hermoso
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68
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69 function out = nthargout (n, varargin)
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70
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71 if (nargin < 2)
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72 print_usage ();
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73 endif
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74
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75 if (isa (varargin{1}, "function_handle") || ischar (varargin{1}))
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76 ntot = max (n(:));
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77 func = varargin{1};
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78 args = varargin(2:end);
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79 elseif (isnumeric (varargin{1})
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80 && (isa (varargin{2}, "function_handle") || ischar (varargin{2})))
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81 ntot = varargin{1};
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82 func = varargin{2};
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83 args = varargin(3:end);
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84 else
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85 print_usage ();
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86 endif
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87
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88 if (any (n != fix (n)) || ntot != fix (ntot) || any (n <= 0) || ntot <= 0)
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89 error ("nthargout: N and NTOT must consist of positive integers");
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90 endif
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91
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92 outargs = cell (1, ntot);
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93
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94 try
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95 [outargs{:}] = feval (func, args{:});
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96 if (numel (n) > 1)
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97 out = outargs(n);
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98 else
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99 out = outargs{n};
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100 endif
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101 catch
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102 err = lasterr ();
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103 if (strfind ("some elements undefined in return list", err))
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104 error ("nthargout: Too many output arguments: %d", ntot);
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105 else
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106 error (err);
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107 endif
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108 end_try_catch
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109
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110 endfunction
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111
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112
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113 %!shared m
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114 %! m = magic (5);
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115 %!assert (nthargout ([1,2], @ind2sub, size (m), nthargout (2, @max, m(:))), {5,3})
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116 %!assert (nthargout (3, @find, m(m>20)), [23, 24, 25, 21, 22]')
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117