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1 ## Copyright (C) 1993, 1994, 1995 Auburn University. All rights reserved. |
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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} {[@var{n}, @var{m}, @var{p}] =} abcddim (@var{a}, @var{b}, @var{c}, @var{d}) |
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21 ## Check for compatibility of the dimensions of the matrices defining |
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22 ## the linear system |
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23 ## @iftex |
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24 ## @tex |
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25 ## $[A, B, C, D]$ corresponding to |
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26 ## $$ |
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27 ## \eqalign{ |
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28 ## {dx\over dt} &= A x + B u\cr |
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29 ## y &= C x + D u} |
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30 ## $$ |
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31 ## @end tex |
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32 ## @end iftex |
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33 ## @ifinfo |
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34 ## [A, B, C, D] corresponding to |
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35 ## |
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36 ## @example |
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37 ## dx/dt = a x + b u |
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38 ## y = c x + d u |
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39 ## @end example |
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40 ## |
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41 ## @end ifinfo |
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42 ## or a similar discrete-time system. |
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43 ## |
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44 ## If the matrices are compatibly dimensioned, then @code{abcddim} returns |
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45 ## |
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46 ## @table @var |
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47 ## @item n |
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48 ## The number of system states. |
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49 ## |
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50 ## @item m |
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51 ## The number of system inputs. |
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52 ## |
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53 ## @item p |
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54 ## The number of system outputs. |
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55 ## @end table |
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56 ## |
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57 ## Otherwise @code{abcddim} returns @var{n} = @var{m} = @var{p} = @minus{}1. |
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58 ## |
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59 ## Note: n = 0 (pure gain block) is returned without warning. |
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60 ## @seealso{is_abcd} |
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61 ## @end deftypefn |
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62 |
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63 ## Author: A. S. Hodel <a.s.hodel@eng.auburn.edu> |
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64 ## Created: August 1993. |
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65 ## a s hodel: modified to accept pure-gain systems aug 1996 |
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66 |
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67 function [n, m, p] = abcddim (a, b, c, d) |
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68 |
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69 if (nargin != 4) |
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70 error ("abcddim: four arguments required"); |
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71 endif |
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72 |
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73 n = m = p = -1; |
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74 |
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75 [a, an, am] = __abcddims__ (a); |
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76 [b, bn, bm] = __abcddims__ (b); |
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77 [c, cn, cm] = __abcddims__ (c); |
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78 [d, dn, dm] = __abcddims__ (d); |
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79 |
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80 if ( (!issquare(a)) & (!isempty(a)) ) |
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81 warning (["abcddim: a is not square (",num2str(an),"x",num2str(am),")"]); |
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82 return |
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83 endif |
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84 |
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85 if( (bm == 0) & (dm == 0) ) |
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86 warning("abcddim: no inputs"); |
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87 elseif (bn != am) |
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88 warning (["abcddim: a(",num2str(an),"x",num2str(am), ... |
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89 " and b(",num2str(bn),"x",num2str(bm),") are not compatible"]); |
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90 return |
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91 endif |
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92 |
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93 if( (cn == 0) & (dn == 0 ) ) |
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94 warning("abcddim: no outputs"); |
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95 elseif (cm != an) |
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96 warning (["abcddim: a(",num2str(an),"x",num2str(am), ... |
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97 " and c(",num2str(cn),"x",num2str(cm),") are not compatible"]); |
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98 return |
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99 endif |
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100 |
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101 have_connections = (bn*cn != 0); |
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102 |
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103 if( (dn == 0) & have_connections) |
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104 warning("abcddim: empty d matrix passed; setting compatibly with b, c"); |
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105 [d, dn, dm] = __abcddims__ (zeros (cn, bm)); |
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106 endif |
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107 |
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108 if(an > 0) |
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109 [dn, dm] = size(d); |
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110 if ( (cn != dn) & have_connections ) |
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111 warning (["abcddim: c(",num2str(cn),"x",num2str(cm), ... |
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112 " and d(",num2str(dn),"x",num2str(dm),") are not compatible"]); |
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113 return |
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114 endif |
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115 |
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116 if ( (bm != dm) & have_connections ) |
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117 warning (["abcddim: b(",num2str(bn),"x",num2str(bm), ... |
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118 " and d(",num2str(dn),"x",num2str(dm),") are not compatible"]); |
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119 return |
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120 endif |
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121 |
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122 m = bm; |
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123 p = cn; |
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124 else |
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125 [p,m] = size(d); |
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126 endif |
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127 n = an; |
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128 endfunction |
