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1 ## Copyright (C) 1996, 1998, 2000, 2002, 2004, 2005, 2006, 2007 |
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2 ## Auburn University. All rights reserved. |
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3 ## |
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4 ## This file is part of Octave. |
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5 ## |
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6 ## Octave is free software; you can redistribute it and/or modify it |
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7 ## under the terms of the GNU General Public License as published by |
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8 ## the Free Software Foundation; either version 3 of the License, or (at |
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9 ## your option) any later version. |
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10 ## |
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11 ## Octave is distributed in the hope that it will be useful, but |
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12 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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13 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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14 ## General Public License for more details. |
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15 ## |
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16 ## You should have received a copy of the GNU General Public License |
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17 ## along with Octave; see the file COPYING. If not, see |
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18 ## <http://www.gnu.org/licenses/>. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {@var{retsys} =} sysprune (@var{asys}, @var{out_idx}, @var{in_idx}) |
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22 ## Extract specified inputs/outputs from a system |
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23 ## |
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24 ## @strong{Inputs} |
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25 ## @table @var |
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26 ## @item asys |
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27 ## system data structure |
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28 ## @item out_idx |
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29 ## @itemx in_idx |
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30 ## Indices or signal names of the outputs and inputs to be kept in the returned |
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31 ## system; remaining connections are ``pruned'' off. |
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32 ## May select as [] (empty matrix) to specify all outputs/inputs. |
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33 ## |
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34 ## @example |
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35 ## retsys = sysprune (Asys, [1:3,4], "u_1"); |
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36 ## retsys = sysprune (Asys, @{"tx", "ty", "tz"@}, 4); |
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37 ## @end example |
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38 ## |
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39 ## @end table |
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40 ## |
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41 ## @strong{Output} |
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42 ## @table @var |
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43 ## @item retsys |
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44 ## Resulting system. |
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45 ## @end table |
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46 ## @example |
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47 ## @group |
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48 ## ____________________ |
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49 ## u1 ------->| |----> y1 |
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50 ## (in_idx) | Asys | (out_idx) |
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51 ## u2 ------->| |----| y2 |
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52 ## (deleted)-------------------- (deleted) |
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53 ## @end group |
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54 ## @end example |
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55 ## @end deftypefn |
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56 |
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57 ## Author: A. S. Hodel <a.s.hodel@eng.auburn.edu> |
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58 ## Created: August 1995 |
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59 ## Updated by John Ingram 7-15-96 |
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60 |
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61 function sys = sysprune (sys, output_idx, input_idx, state_idx) |
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62 |
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63 if (nargin < 3 || nargin > 4) |
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64 print_usage (); |
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65 elseif (nargin < 4) |
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66 state_idx = []; |
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67 endif |
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68 |
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69 ## default: no action |
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70 [nn, nz, mm, pp] = sysdimensions (sys); |
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71 if (isempty (output_idx)) |
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72 output_idx = 1:pp; |
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73 endif |
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74 if (isempty (input_idx)) |
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75 input_idx = 1:mm; |
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76 endif |
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77 if (isempty (state_idx)) |
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78 state_idx = 1:(nn+nz); |
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79 endif |
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80 |
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81 ## check for signal names |
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82 if (is_signal_list (output_idx) || ischar (output_idx)) |
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83 output_idx = sysidx (sys, "out", output_idx); |
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84 endif |
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85 if (is_signal_list (input_idx) || ischar (input_idx)) |
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86 input_idx = sysidx (sys, "in", input_idx); |
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87 endif |
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88 |
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89 ## check dimensions |
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90 if (! (isvector (output_idx) || isempty (output_idx))) |
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91 if (! ismatrix (output_idx)) |
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92 error ("sysprune: bad argument passed for output_idx"); |
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93 else |
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94 error ("sysprune: output_idx (%d x %d) must be a vector or empty", |
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95 rows (output_idx), columns (output_idx)); |
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96 endif |
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97 elseif (is_duplicate_entry (output_idx)) |
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98 error ("sysprune: duplicate entries found in output_idx"); |
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99 endif |
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100 |
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101 if (! (isvector (input_idx) || isempty (input_idx))) |
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102 if (! ismatrix (input_idx)) |
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103 error ("sysprune: bad argument passed for input_idx"); |
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104 else |
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105 error ("sysprune: input_idx (%d x %d) must be a vector or empty", |
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106 rows (input_idx), columns(input_idx)); |
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107 endif |
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108 elseif (is_duplicate_entry (input_idx)) |
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109 error ("sysprune: duplicate entries found in input_idx"); |
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110 endif |
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111 |
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112 if (! (isvector (state_idx) || isempty (state_idx))) |
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113 if (! ismatrix (state_idx)) |
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114 error ("sysprune: bad argument passed for state_idx"); |
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115 else |
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116 error ("sysprune: state_idx (%d x %d) must be a vector or empty", |
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117 rows (state_idx), columns (state_idx)); |
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118 endif |
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119 elseif (nn+nz > 0) |
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120 if (is_duplicate_entry (state_idx)) |
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121 error ("sysprune: duplicate entries found in state_idx"); |
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122 endif |
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123 endif |
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124 |
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125 lo = length (output_idx); |
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126 li = length (input_idx); |
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127 lst = length (state_idx); |
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128 |
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129 if (! isstruct (sys)) |
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130 error ("Asys must be a system data structure (see ss, tf, or zp)"); |
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131 elseif (pp < lo) |
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132 error("%d output_idx entries, system has only %d outputs", lo, pp]); |
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133 elseif (mm < li) |
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134 error("%d input_idx entries, system has only %d inputs", li, mm); |
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135 elseif (nn+nz < lst) |
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136 error("%d state_idx entries, system has only %d states", lst, nn+nz); |
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137 endif |
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138 |
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139 [aa, bb, cc, dd, tsam, nn, nz, stnam, innam, outnam, yd] = sys2ss (sys); |
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140 |
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141 ## check for valid state permutation |
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142 if (nn & nz) |
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143 c_idx = find (state_idx <= nn); |
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144 if (! isempty (c_idx)) |
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145 max_c = max (c_idx); |
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146 else |
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147 max_c = 0; |
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148 endif |
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149 d_idx = find (state_idx > nn); |
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150 if (! isempty (d_idx)) |
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151 min_d = min (d_idx); |
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152 else |
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153 min_d = nn+nz; |
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154 endif |
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155 if (max_c > min_d) |
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156 warning ("sysprune: state_idx(%d)=%d (discrete) preceeds", |
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157 min_d, state_idx(min_d)); |
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158 warning(" state_idx(%d)=%d (continuous)", |
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159 max_c, state_idx(max_c)); |
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160 warning ("sysprune: sys has %d continuous states, %d discrete states", |
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161 nn, nz); |
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162 error("continuous/discrete state partition not preserved; see ss"); |
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163 endif |
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164 endif |
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165 |
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166 idx = input_idx; |
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167 odx = output_idx; |
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168 if (isempty (state_idx)) |
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169 idx = []; |
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170 odx = []; |
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171 endif |
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172 aa = aa(state_idx,state_idx); |
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173 bb = bb(state_idx,idx); |
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174 cc = cc(odx,state_idx); |
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175 dd = dd(output_idx,input_idx); |
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176 yd = yd(output_idx); |
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177 |
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178 innam = innam(input_idx); |
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179 outnam = outnam(output_idx); |
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180 stnam = stnam(state_idx); |
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181 nn1 = length (find (state_idx <= nn)); |
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182 nz1 = length (find (state_idx > nn)); |
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183 |
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184 sys = ss (aa, bb, cc, dd, tsam, nn1, nz1, stnam, innam, outnam, find (yd)); |
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185 |
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186 endfunction |
