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1 # Copyright (C) 1996,1999 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 the |
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7 # Free Software Foundation; either version 2, or (at your option) any |
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8 # later version. |
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9 # |
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10 # Octave is distributed in the hope that it will be useful, but WITHOUT |
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11 # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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12 # FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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13 # 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, write to the Free |
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17 # Software Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA. |
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18 |
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19 function sys = sysadd(...) |
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20 # |
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21 # sys = sysadd(Gsys{,Hsys,...}) |
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22 # |
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23 # returns transfer function sys = Gsys + Hsys + ... |
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24 # |
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25 # Method: sysgroup used to connect systems in parallel |
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26 # The input vector is connected to all systems; the outputs are summed. |
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27 # Returned system input/output signal names are those of Gsys. For |
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28 # example, sysadd(Gsys,Hsys) results in |
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29 # |
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30 # ________ |
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31 # ----| Gsys |--- |
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32 # u | ---------- +| |
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33 # ----- (_)----> y |
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34 # | ________ +| |
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35 # ----| Hsys |--- |
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36 # -------- |
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37 |
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38 # Written by John Ingram July 1996 |
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39 # Updated for variable number of arguments July 1999 A. S. Hodel |
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40 |
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41 save_val = implicit_str_to_num_ok; # save for later |
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42 implicit_str_to_num_ok = 1; |
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43 |
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44 if(nargin < 1) |
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45 usage("sysadd: sys = sysysadd(Gsys{,Hsys, ...})"); |
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46 endif |
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47 |
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48 # collect all arguments |
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49 arglist = list(); |
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50 va_start(); |
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51 for kk=1:nargin |
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52 arglist(kk) = va_arg(); |
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53 if(!is_struct(nth(arglist,kk))) |
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54 error("sysadd: argument %d is not a data structure",kk); |
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55 endif |
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56 endfor |
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57 |
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58 # check system dimensions |
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59 [n,nz,mg,pg,Gyd] = sysdimensions(nth(arglist,1)); |
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60 for kk=2:nargin |
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61 [n,nz,mh,ph,Hyd] = sysdimensions(nth(arglist,kk)); |
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62 if(mg != mh) |
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63 error("arg 1 has %d inputs; arg %d has vs %d inputs",mg,kk,mh); |
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64 elseif(pg != ph) |
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65 error("arg 1 has %d outputs; arg %d has vs %d outputs",pg,kk,ph); |
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66 elseif(norm(Gyd - Hyd)) |
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67 warning("cannot add a discrete output to a continuous output"); |
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68 error("Output type mismatch: arguments 1 and %d\n",kk); |
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69 endif |
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70 endfor |
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71 |
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72 # perform the add |
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73 if(nargin == 2) |
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74 Gsys = nth(arglist,1); Hsys = nth(arglist,2); |
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75 if( strcmp(sysgettype(Gsys),"tf") | strcmp(sysgettype(Hsys),"tf") ) |
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76 # see if adding transfer functions with identical denominators |
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77 [Gnum,Gden,GT,Gin,Gout] = sys2tf(Gsys); |
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78 [Hnum,Hden,HT,Hin,Hout] = sys2tf(Hsys); |
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79 if(length(Hden) == length(Gden) ) |
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80 if( (Hden == Gden) & (HT == GT) ) |
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81 sys = tf2sys(Gnum+Hnum,Gden,GT,Gin,Gout); |
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82 return |
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83 endif |
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84 # if not, we go on and do the usual thing... |
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85 endif |
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86 endif |
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87 |
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88 # make sure in ss form |
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89 Gsys = sysupdate(Gsys,"ss"); |
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90 Hsys = sysupdate(Hsys,"ss"); |
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91 |
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92 # change signal names to avoid warning messages from sysgroup |
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93 Gsys = syssetsignals(Gsys,"in",sysdefioname(length(Gin),"Gin_u")); |
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94 Gsys = syssetsignals(Gsys,"out",sysdefioname(length(Gout),"Gout_u")); |
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95 Hsys = syssetsignals(Hsys,"in",sysdefioname(length(Hin),"Hin_u")); |
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96 Hsys = syssetsignals(Hsys,"out",sysdefioname(length(Hout),"Hout_u")); |
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97 |
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98 sys = sysgroup(Gsys,Hsys); |
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99 |
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100 eyin = eye(mg); |
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101 eyout = eye(pg); |
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102 |
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103 sys = sysscale(sys,[eyout, eyout],[eyin;eyin],Gout,Gin); |
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104 |
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105 else |
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106 # multiple systems (or a single system); combine together one by one |
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107 sys = nth(arglist,1); |
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108 for kk=2:length(arglist) |
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109 sys = sysadd(sys,nth(arglist,kk)); |
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110 endfor |
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111 endif |
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112 endfunction |
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113 |
