Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / odepkg-0.8.2 / odephas3.m

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+%# Copyright (C) 2006-2012, Thomas Treichl <treichl@users.sourceforge.net>
+%# OdePkg - A package for solving ordinary differential equations and more
+%#
+%# This program 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 of the License, or
+%# (at your option) any later version.
+%#
+%# 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; If not, see <http://www.gnu.org/licenses/>.
+
+%# -*- texinfo -*-
+%# @deftypefn {Function File} {[@var{ret}] =} odephas3 (@var{t}, @var{y}, @var{flag})
+%#
+%# Open a new figure window and plot the first result from the variable @var{y} that is of type double column vector over the second and the third result from the variable @var{y} while solving. The types and the values of the input parameter @var{t} and the output parameter @var{ret} depend on the input value @var{flag} that is of type string. If @var{flag} is
+%# @table @option
+%# @item  @code{"init"}
+%# then @var{t} must be a double column vector of length 2 with the first and the last time step and nothing is returned from this function,
+%# @item  @code{""}
+%# then @var{t} must be a double scalar specifying the actual time step and the return value is false (resp. value 0) for 'not stop solving',
+%# @item  @code{"done"}
+%# then @var{t} must be a double scalar specifying the last time step and nothing is returned from this function.
+%# @end table
+%#
+%# This function is called by a OdePkg solver function if it was specified in an OdePkg options structure with the @command{odeset}. This function is an OdePkg internal helper function therefore it should never be necessary that this function is called directly by a user. There is only little error detection implemented in this function file to achieve the highest performance.
+%#
+%# For example, solve the "Lorenz attractor" and display the results while solving in a 3D plane
+%# @example
+%# function vyd = florenz (vt, vx)
+%#   vyd = [10 * (vx(2) - vx(1));
+%#          vx(1) * (28 - vx(3));
+%#          vx(1) * vx(2) - 8/3 * vx(3)];
+%# endfunction
+%#
+%# vopt = odeset ('OutputFcn', @@odephas3); 
+%# vsol = ode23 (@@florenz, [0:0.01:7.5], [3 15 1], vopt);
+%# @end example
+%# @end deftypefn
+%#
+%# @seealso{odepkg}
+
+function [varargout] = odephas3 (vt, vy, vflag)
+
+  %# vt and vy are always column vectors, vflag can be either 'init'
+  %# or [] or 'done'. If 'init' then varargout{1} = [], if [] the
+  %# varargout{1} either true or false, if 'done' then varargout{1} = [].
+  persistent vfigure; persistent vyold; persistent vcounter;
+
+  if (strcmp (vflag, 'init'))
+    %# vt is either the time slot [tstart tstop] or [t0, t1, ..., tn]
+    %# vy is the inital value vector vinit from the caller function
+    vfigure = figure; vyold = vy(:,1); vcounter = 1;
+
+  elseif (isempty (vflag))
+    %# Return something in varargout{1}, either false for 'not stopping
+    %# the integration' or true for 'stopping the integration'
+    vcounter = vcounter + 1; figure (vfigure);
+    vyold(:,vcounter) = vy(:,1);
+    plot3 (vyold(1,:), vyold(2,:), vyold (3,:), '-o', 'markersize', 1);
+    drawnow; varargout{1} = false;
+
+  elseif (strcmp (vflag, 'done'))
+    %# Cleanup has to be done, clear the persistent variables because
+    %# we don't need them anymore
+    clear ('vfigure', 'vyold', 'vcounter');
+
+  end
+
+%# Local Variables: ***
+%# mode: octave ***
+%# End: ***