Mercurial > octave
view scripts/control/sysprune.m @ 3236:98e15955107e
[project @ 1999-03-05 07:17:10 by jwe]
author | jwe |
---|---|
date | Fri, 05 Mar 1999 07:19:35 +0000 |
parents | 28aba52a2368 |
children | 6dd06d525de6 |
line wrap: on
line source
# Copyright (C) 1996,1998 A. Scottedward Hodel # # This file is part of Octave. # # Octave is free software; you can redistribute it and/or modify it # under the terms of the GNU General Public License as published by the # Free Software Foundation; either version 2, or (at your option) any # later version. # # Octave is distributed in the hope that it will be useful, but WITHOUT # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or # FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License # for more details. # # You should have received a copy of the GNU General Public License # along with Octave; see the file COPYING. If not, write to the Free # Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. function sys = sysprune(sys,output_idx,input_idx,state_idx) # function retsys = sysprune(Asys,output_idx,input_idx{,state_idx}) # Extract/permute specified inputs, outputs, and/or states of a system. # # inputs: # Asys: system data structure # output_idx,input_idx: list of connections indices; the new # system has outputs y(output_idx(ii)) and inputs u(input_idx(ii)). # May select as [] (empty matrix) to specify all outputs/inputs. # state_idx: optional argument; list of indices of states to keep # in the reduced model. May omit this argument or pass [] (empty # matrix) to keep all states in the returned model # # output: retsys: resulting system: # ____________________ # | | # u1 ----->| |----> y1 # (input_idx) | Asys | (output_idx) # | | # u2 (deleted) |---->| |----| y2 (deleted) # | | # -------------------- # A. S. Hodel August 1995 # Updated by John Ingram 7-15-96 if( nargin < 3 | nargin > 4 ) usage("retsys = sysprune(sys,output_idx,input_idx{,state_idx})"); elseif(nargin < 4) state_idx = []; endif # default: no action [nn,nz,mm,pp] = sysdimensions(sys); if(isempty(output_idx)) output_idx = 1:pp; endif if(isempty(input_idx)) input_idx = 1:mm; endif if(isempty(state_idx)) state_idx = 1:(nn+nz); endif # check dimensions if( !(is_vector(output_idx) | isempty(output_idx) ) ) if(!is_matrix(output_idx)) error("sysprune: bad argument passed for output_idx"); else error("sysprune: output_idx (%d x %d) must be a vector or empty", ... rows(output_idx),columns(output_idx)); endif elseif(is_duplicate_entry(output_idx)) error("sysprune: duplicate entries found in output_idx"); endif if( !(is_vector(input_idx) | isempty(input_idx) ) ) if(!is_matrix(input_idx)) error("sysprune: bad argument passed for input_idx"); else error("sysprune: input_idx (%d x %d) must be a vector or empty", ... rows(input_idx),columns(input_idx)); endif elseif(is_duplicate_entry(input_idx)) error("sysprune: duplicate entries found in input_idx"); endif if( !(is_vector(state_idx) | isempty(state_idx) ) ) if(!is_matrix(state_idx)) error("sysprune: bad argument passed for state_idx"); else error("sysprune: state_idx (%d x %d) must be a vector or empty", ... rows(state_idx),columns(state_idx)); endif elseif(nn+nz > 0) if(is_duplicate_entry(state_idx)) error("sysprune: duplicate entries found in state_idx"); endif endif lo = length(output_idx); li = length(input_idx); lst = length(state_idx); if( !is_struct(sys)) error("Asys must be a system data structure (see ss2sys, tf2sys, or zp2sys)") elseif(pp < lo) error([num2str(lo)," output_idx entries, system has only ", ... num2str(pp)," outputs"]); elseif(mm < li) error([num2str(li)," input_idx entries, system has only ", ... num2str(mm)," inputs"]); elseif(nn+nz < lst) error([num2str(lst)," state_idx entries, system has only ", ... num2str(nn+nz)," states"]); endif [aa,bb,cc,dd,tsam,nn,nz,stnam,innam,outnam,yd] = sys2ss(sys); # check for legal state permutation if(nn & nz) c_idx = find(state_idx <= nn); if(!isempty(c_idx)) max_c = max(c_idx); else max_c = 0; endif d_idx = find(state_idx > nn); if(!isempty(d_idx)) min_d = min(d_idx); else min_d = nn+nz; endif if(max_c > min_d) warning("sysprune: state_idx(%d)=%d (discrete) preceeds", ... min_d,state_idx(min_d)); warning(" state_idx(%d)=%d (continuous)",... max_c,state_idx(max_c)); warning("sysprune: sys has %d continuous states, %d discrete states", ... nn,nz); error("continuous/discrete state partition not preserved ; see ss2sys"); endif endif idx = input_idx; odx = output_idx; if(isempty(state_idx)) idx = []; odx = []; endif aa = aa(state_idx,state_idx); bb = bb(state_idx,idx); cc = cc(odx,state_idx); dd = dd(output_idx,input_idx); yd = yd(output_idx); innam = innam(input_idx); outnam = outnam(output_idx); stnam = stnam(state_idx); nn1 = length(find(state_idx <= nn)); nz1 = length(find(state_idx > nn)); sys = ss2sys(aa,bb,cc,dd,tsam,nn1,nz1,stnam,innam,outnam,find(yd)); endfunction