--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/scripts/control/system/ss.m	Tue Feb 17 02:34:33 2004 +0000
@@ -0,0 +1,287 @@
+## Copyright (C) 1996, 1998 Auburn University.  All rights reserved.
+##
+## 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, 59 Temple Place, Suite 330, Boston, MA 02111 USA.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} ss (@var{a}, @var{b}, @var{c}, @var{d}, @var{tsam}, @var{n}, @var{nz}, @var{stname}, @var{inname}, @var{outname}, @var{outlist})
+## Create system structure from state-space data.   May be continous,
+## discrete, or mixed (sampeled-data)
+##
+## @strong{Inputs}
+## @table @var
+## @item a
+## @itemx b
+## @itemx c
+## @itemx d
+## usual state space matrices.
+##
+## default: @var{d} = zero matrix
+##
+## @item   tsam
+## sampling rate.  Default: @math{tsam = 0} (continuous system)
+##
+## @item n
+## @itemx nz
+## number of continuous, discrete states in the system
+##
+## If @var{tsam} is 0, @math{n = @code{rows}(@var{a})}, @math{nz = 0}.
+##
+## If @var{tsam} is greater than zero, @math{n = 0},
+## @math{nz = @code{rows}(@var{a})}
+##
+## see below for system partitioning
+##
+## @item  stname
+## list of strings of state signal names
+##
+## default (@var{stname}=[] on input): @code{x_n} for continuous states,
+##                     @code{xd_n} for discrete states
+##
+## @item inname
+## list of strings of input signal names
+##
+## default (@var{inname} = [] on input): @code{u_n}
+##
+## @item outname
+## list of strings of input signal names
+##
+## default (@var{outname} = [] on input): @code{y_n}
+##
+## @item   outlist
+##
+## list of indices of outputs y that are sampled
+##
+## If @var{tsam} is 0, @math{outlist = []}.
+##
+## If @var{tsam} is greater than 0, @math{outlist = 1:@code{rows}(@var{c})}.
+## @end table
+##
+## Unlike states, discrete/continous outputs may appear in any order.
+##
+## @strong{Note} @code{sys2ss} returns a vector @var{yd} where
+## @var{yd}(@var{outlist}) = 1; all other entries of @var{yd} are 0.
+##
+## @strong{Outputs}
+## @var{outsys} = system data structure
+##
+## @strong{System partitioning}
+##
+## Suppose for simplicity that outlist specified
+## that the first several outputs were continuous and the remaining outputs
+## were discrete.  Then the system is partitioned as
+## @example
+## @group
+## x = [ xc ]  (n x 1)
+##     [ xd ]  (nz x 1 discrete states)
+## a = [ acc acd ]  b = [ bc ]
+##     [ adc add ]      [ bd ]
+## c = [ ccc ccd ]  d = [ dc ]
+##     [ cdc cdd ]      [ dd ]
+##
+##     (cdc = c(outlist,1:n), etc.)
+## @end group
+## @end example
+## with dynamic equations:
+## @ifinfo
+## @math{d/dt xc(t)     = acc*xc(t)      + acd*xd(k*tsam) + bc*u(t)}
+##
+## @math{xd((k+1)*tsam) = adc*xc(k*tsam) + add*xd(k*tsam) + bd*u(k*tsam)}
+##
+## @math{yc(t)      = ccc*xc(t)      + ccd*xd(k*tsam) + dc*u(t)}
+##
+## @math{yd(k*tsam) = cdc*xc(k*tsam) + cdd*xd(k*tsam) + dd*u(k*tsam)}
+## @end ifinfo
+## @iftex
+## @tex
+## $$\eqalign{
+## {d \over dt} x_c(t)
+##   & =   a_{cc} x_c(t)      + a_{cd} x_d(k*t_{sam}) + bc*u(t) \cr
+## x_d((k+1)*t_{sam})
+##   & =   a_{dc} x_c(k t_{sam}) + a_{dd} x_d(k t_{sam}) + b_d u(k t_{sam}) \cr
+## y_c(t)
+##  & =  c_{cc} x_c(t) + c_{cd} x_d(k t_{sam}) + d_c u(t) \cr
+## y_d(k t_{sam})
+##   & =  c_{dc} x_c(k t_{sam}) + c_{dd} x_d(k t_{sam}) + d_d u(k t_{sam})
+## }$$
+## @end tex
+## @end iftex
+##
+## @strong{Signal partitions}
+## @example
+## @group
+##         | continuous      | discrete               |
+## ----------------------------------------------------
+## states  | stname(1:n,:)   | stname((n+1):(n+nz),:) |
+## ----------------------------------------------------
+## outputs | outname(cout,:) | outname(outlist,:)     |
+## ----------------------------------------------------
+## @end group
+## @end example
+## where @math{cout} is the list of in 1:@code{rows}(@var{p})
+## that are not contained in outlist. (Discrete/continuous outputs
+## may be entered in any order desired by the user.)
+##
+## @strong{Example}
+## @example
+## octave:1> a = [1 2 3; 4 5 6; 7 8 10];
+## octave:2> b = [0 0 ; 0 1 ; 1 0];
+## octave:3> c = eye(3);
+## octave:4> sys = ss(a,b,c,[],0,3,0,list("volts","amps","joules"));
+## octave:5> sysout(sys);
+## Input(s)
+##         1: u_1
+##         2: u_2
+##
+## Output(s):
+##         1: y_1
+##         2: y_2
+##         3: y_3
+##
+## state-space form:
+## 3 continuous states, 0 discrete states
+## State(s):
+##         1: volts
+##         2: amps
+##         3: joules
+##
+## A matrix: 3 x 3
+##    1   2   3
+##    4   5   6
+##    7   8  10
+## B matrix: 3 x 2
+##   0  0
+##   0  1
+##   1  0
+## C matrix: 3 x 3
+##   1  0  0
+##   0  1  0
+##   0  0  1
+## D matrix: 3 x 3
+##   0  0
+##   0  0
+##   0  0
+## @end example
+## Notice that the @math{D} matrix is constructed  by default to the
+## correct dimensions.  Default input and output signals names were assigned
+## since none were given.
+## @end deftypefn
+
+## Author: John Ingram <ingraje@eng.auburn.edu>
+## Created: July 20, 1996
+
+function retsys = ss (a, b, c, d, tsam, n, nz, stname, inname, outname, outlist)
+
+  ## Test for correct number of inputs
+  if ((nargin < 3) | (nargin > 11))
+    usage("retsys = ss  (a,b,c{,d,tsam,n,nz,stname,inname,outname,outlist})");
+  endif
+
+  ## verify A, B, C, D arguments
+  ## If D is not specified, set it to a zero matrix of appriate dimension.
+  if (nargin == 3)          d = zeros(rows(c) , columns(b));
+  elseif (isempty(d))       d = zeros(rows(c) , columns(b));      endif
+
+  ## Check the dimensions
+  [na,m,p] = abcddim(a,b,c,d);
+
+  ## If dimensions are wrong, exit function
+  if (m == -1)
+    error("a(%dx%d), b(%dx%d), c(%dx%d), d(%dx%d); incompatible", ...
+      rows(a), columns(a), rows(b), columns(b), rows(c), columns(c), ...
+      rows(d), columns(d));
+  endif
+
+  ## check for tsam input
+  if(nargin < 5) tsam = 0;
+  elseif( !( is_sample(tsam) | (tsam == 0) ) )
+    error("tsam must be a nonnegative real scalar");
+  endif
+
+  ## check for continuous states
+  if( (nargin < 6) & (tsam == 0) )               n = na;
+  elseif(nargin < 6)                             n = 0;
+  elseif((!ismatrix(n)) | isstr(n))
+    error("Parameter n is not a numerical value.");
+  elseif( (!isscalar(n)) | (n < 0 ) | (n != round(n)) )
+    if(isscalar(n))     error("invalid value of n=%d,%e",n,n);
+    else                 error("invalid value of n=(%dx%d)", ...
+                           rows(n), columns(n));                endif
+  endif
+
+  ## check for num discrete states
+  if( (nargin < 7) & (tsam == 0))               nz = 0;
+  elseif(nargin < 7)                            nz = na - n;
+  elseif((!ismatrix(nz)) | isstr(nz))
+    error("Parameter nz is not a numerical value.");
+  elseif( (!isscalar(nz)) | (nz < 0 ) | (nz != round(nz)) )
+    if(isscalar(nz))
+      error(["invalid value of nz=",num2str(nz)]);
+    else
+      error(["invalid value of nz=(",num2str(rows(nz)),"x", ...
+        num2str(columns(nz)),")"]);
+    endif
+  endif
+
+  ## check for total number of states
+  if( (n + nz) != na )
+    error(["invalid: a is ",num2str(na),"x",num2str(na),", n=", ...
+        num2str(n),", nz=",num2str(nz)]);
+  endif
+
+  ## construct system with default names
+  retsys.a = a;
+  retsys.b = b;
+  retsys.c = c;
+  retsys.d = d;
+
+  retsys.n = n;
+  retsys.nz = nz;
+  retsys.tsam = tsam;
+  retsys.yd = zeros(1,p);     # default value entered below
+
+  ## Set the system vector:  active = 2(ss), updated = [0 0 1];
+  retsys.sys = [2, 0, 0, 1];
+
+  retsys.stname = __sysdefstname__ (n, nz);
+  retsys.inname = __sysdefioname__ (m, "u");
+  retsys.outname = __sysdefioname__ (p, "y");
+
+  ## check for state names
+  if(nargin >= 8)
+    if(!isempty(stname)) retsys = syssetsignals(retsys,"st",stname); endif
+  endif
+
+  ## check for input names
+  if(nargin >= 9)
+    if(!isempty(inname)) retsys = syssetsignals(retsys,"in",inname); endif
+  endif
+
+  ## check for output names
+  if(nargin >= 10)
+    if(!isempty(outname)) retsys = syssetsignals(retsys,"out",outname); endif
+  endif
+
+  ## set up yd
+  if(nargin < 11)
+    retsys = syssetsignals(retsys,"yd",ones(1,p)*(tsam > 0));
+  else
+    if(!isempty(outlist))
+      retsys = syssetsignals(retsys,"yd",ones(size(outlist)),outlist);
+    endif
+  endif
+
+endfunction