Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / ocs-0.1.3 / nls / nls_stationary.m

diff --git a/octave_packages/ocs-0.1.3/nls/nls_stationary.m b/octave_packages/ocs-0.1.3/nls/nls_stationary.m
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+## Copyright (C) 2006,2007,2008  Carlo de Falco            
+##
+## This file is part of:
+## OCS - A Circuit Simulator for Octave
+##
+## OCS 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.
+##
+## This program 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 this program (see the file LICENSE); if not,
+## see <http://www.gnu.org/licenses/>.
+##
+## author: Carlo de Falco <cdf _AT_ users.sourceforge.net> 
+
+## -*- texinfo -*-
+## @deftypefn{Function File} {[@var{out}, @var{niter}]} = nls_stationary @
+## (@var{instruct},@var{x},@var{tol},@var{maxit})
+## Compute the stationary state solution @var{out} of the system described
+## by @var{instruct}.
+##
+## @var{x} is the initial guess used by the Newton-Raphson algorithm implemented in
+## @code{nls_newton_raphson}, while @var{tol} and @var{maxit} are the corresponding 
+## parameters.
+## 
+## The optional output @var{niter} returns the number of Newton iterations
+## needed to reach convergence.
+##
+## @seealso{nls_newton_raphson}
+## @end deftypefn
+
+function [out, varargout] = nls_stationary(outstruct,x,tol,maxit)
+
+  ## Check input
+  ## FIXME: add input check!
+  if nargin != 4
+    error("nls_stationary: wrong number of input parameters.");
+  endif
+
+  [A0,B,C] = asm_initialize_system(outstruct,x);
+  JAC = @(x) TSTSTATFUNJAC(outstruct,x,B);
+  RES = @(x) TSTSTATFUNRES(outstruct,x,B,C);
+  UPD = @(x) TSTSTATUP(outstruct,x);
+  [out,ii,resnrm] = nls_newton_raphson(x,RES,JAC,tol,maxit,0,UPD);
+
+  if nargin > 1
+    varargout{1} = ii;
+  endif
+
+endfunction
+
+## Jacobian for steady state problems
+function lhs = TSTSTATFUNJAC(outstruct,x,B,Jac,res)
+
+  if nargin < 5
+    [A1,Jac,res] = asm_build_system(outstruct,x,0);
+  endif
+  lhs = (B + Jac); 
+
+endfunction
+## Residual for steady state problem
+function rhs = TSTSTATFUNRES(outstruct,x,B,C,Jac,res)
+
+  if nargin < 6
+    [A1,Jac,res] = asm_build_system(outstruct,x,0);
+  endif
+  rhs = (res + C + B*x);
+
+endfunction
+## Update for transient problem
+function update = TSTSTATUP(outstruct,x)
+
+  [A1,Jac,res] = asm_build_system(outstruct,x,0);
+  update = {Jac,res};
+
+endfunction
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