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1 /* |
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2 |
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3 Copyright (C) 1996, 1997 John W. Eaton |
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4 |
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5 This file is part of Octave. |
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6 |
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7 Octave is free software; you can redistribute it and/or modify it |
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8 under the terms of the GNU General Public License as published by the |
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9 Free Software Foundation; either version 2, or (at your option) any |
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10 later version. |
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11 |
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12 Octave is distributed in the hope that it will be useful, but WITHOUT |
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13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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15 for more details. |
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16 |
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17 You should have received a copy of the GNU General Public License |
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18 along with Octave; see the file COPYING. If not, write to the Free |
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19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
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20 |
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21 */ |
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22 |
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23 // Author: A. S. Hodel <scotte@eng.auburn.edu> |
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24 |
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25 #ifdef HAVE_CONFIG_H |
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26 #include <config.h> |
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27 #endif |
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28 |
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29 #include "defun-dld.h" |
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30 #include "error.h" |
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31 #include "gripes.h" |
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32 #include "oct-obj.h" |
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33 #include "utils.h" |
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34 |
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35 DEFUN_DLD (syl, args, nargout, |
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36 "-*- texinfo -*-\n\ |
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37 @deftypefn {Loadable Function} {@var{x} =} syl (@var{a}, @var{b}, @var{c})\n\ |
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38 Solve the Sylvester equation\n\ |
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39 @iftex\n\ |
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40 @tex\n\ |
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41 $$\n\ |
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42 A X + X B + C = 0\n\ |
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43 $$\n\ |
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44 @end tex\n\ |
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45 @end iftex\n\ |
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46 @ifinfo\n\ |
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47 \n\ |
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48 @example\n\ |
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49 A X + X B + C = 0\n\ |
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50 @end example\n\ |
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51 @end ifinfo\n\ |
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52 using standard @sc{Lapack} subroutines. For example,\n\ |
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53 \n\ |
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54 @example\n\ |
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55 @group\n\ |
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56 syl ([1, 2; 3, 4], [5, 6; 7, 8], [9, 10; 11, 12])\n\ |
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57 @result{} [ -0.50000, -0.66667; -0.66667, -0.50000 ]\n\ |
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58 @end group\n\ |
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59 @end example\n\ |
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60 @end deftypefn") |
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61 { |
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62 octave_value retval; |
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63 |
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64 int nargin = args.length (); |
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65 |
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66 if (nargin != 3 || nargout > 1) |
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67 { |
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68 print_usage ("syl"); |
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69 return retval; |
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70 } |
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71 |
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72 octave_value arg_a = args(0); |
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73 octave_value arg_b = args(1); |
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74 octave_value arg_c = args(2); |
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75 |
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76 int a_nr = arg_a.rows (); |
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77 int a_nc = arg_a.columns (); |
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78 |
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79 int b_nr = arg_b.rows (); |
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80 int b_nc = arg_b.columns (); |
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81 |
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82 int c_nr = arg_c.rows (); |
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83 int c_nc = arg_c.columns (); |
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84 |
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85 int arg_a_is_empty = empty_arg ("syl", a_nr, a_nc); |
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86 int arg_b_is_empty = empty_arg ("syl", b_nr, b_nc); |
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87 int arg_c_is_empty = empty_arg ("syl", c_nr, c_nc); |
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88 |
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89 if (arg_a_is_empty > 0 && arg_b_is_empty > 0 && arg_c_is_empty > 0) |
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90 return octave_value (Matrix ()); |
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91 else if (arg_a_is_empty || arg_b_is_empty || arg_c_is_empty) |
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92 return retval; |
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93 |
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94 // Arguments are not empty, so check for correct dimensions. |
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95 |
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96 if (a_nr != a_nc || b_nr != b_nc) |
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97 { |
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98 gripe_square_matrix_required ("syl: first two parameters:"); |
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99 return retval; |
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100 } |
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101 else if (a_nr != c_nr || b_nr != c_nc) |
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102 { |
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103 gripe_nonconformant (); |
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104 return retval; |
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105 } |
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106 |
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107 // Dimensions look o.k., let's solve the problem. |
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108 |
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109 if (arg_a.is_complex_type () |
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110 || arg_b.is_complex_type () |
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111 || arg_c.is_complex_type ()) |
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112 { |
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113 // Do everything in complex arithmetic; |
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114 |
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115 ComplexMatrix ca = arg_a.complex_matrix_value (); |
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116 |
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117 if (error_state) |
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118 return retval; |
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119 |
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120 ComplexMatrix cb = arg_b.complex_matrix_value (); |
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121 |
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122 if (error_state) |
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123 return retval; |
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124 |
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125 ComplexMatrix cc = arg_c.complex_matrix_value (); |
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126 |
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127 if (error_state) |
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128 return retval; |
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129 |
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130 retval = Sylvester (ca, cb, cc); |
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131 } |
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132 else |
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133 { |
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134 // Do everything in real arithmetic. |
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135 |
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136 Matrix ca = arg_a.matrix_value (); |
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137 |
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138 if (error_state) |
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139 return retval; |
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140 |
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141 Matrix cb = arg_b.matrix_value (); |
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142 |
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143 if (error_state) |
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144 return retval; |
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145 |
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146 Matrix cc = arg_c.matrix_value (); |
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147 |
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148 if (error_state) |
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149 return retval; |
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150 |
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151 retval = Sylvester (ca, cb, cc); |
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152 } |
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153 |
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154 return retval; |
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155 } |
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156 |
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157 /* |
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158 ;;; Local Variables: *** |
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159 ;;; mode: C++ *** |
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160 ;;; End: *** |
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161 */ |
