Mercurial > octave
view scripts/ode/odeplot.m @ 33577:2506c2d30b32 bytecode-interpreter tip
maint: Merge default to bytecode-interpreter
author | Arun Giridhar <arungiridhar@gmail.com> |
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date | Sat, 11 May 2024 18:49:01 -0400 |
parents | 2e484f9f1f18 |
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######################################################################## ## ## Copyright (C) 2006-2024 The Octave Project Developers ## ## See the file COPYRIGHT.md in the top-level directory of this ## distribution or <https://octave.org/copyright/>. ## ## 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 3 of the License, 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, see ## <https://www.gnu.org/licenses/>. ## ######################################################################## ## -*- texinfo -*- ## @deftypefn {} {@var{stop_solve} =} odeplot (@var{t}, @var{y}, @var{flag}) ## ## Open a new figure window and plot the solution of an ode problem at each ## time step during the integration. ## ## The types and values of the input parameters @var{t} and @var{y} depend on ## the input @var{flag} that is of type string. Valid values of @var{flag} ## are: ## ## @table @option ## @item @qcode{"init"} ## The input @var{t} must be a column vector of length 2 with the first and ## last time step (@code{[@var{tfirst} @var{tlast}]}. The input @var{y} ## contains the initial conditions for the ode problem (@var{y0}). ## ## @item @qcode{""} ## The input @var{t} must be a scalar double or vector specifying the time(s) ## for which the solution in input @var{y} was calculated. ## ## @item @qcode{"done"} ## The inputs should be empty, but are ignored if they are present. ## @end table ## ## @code{odeplot} always returns false, i.e., don't stop the ode solver. ## ## Example: solve an anonymous implementation of the ## @nospell{@qcode{"Van der Pol"}} equation and display the results while ## solving. ## ## @example ## @group ## fvdp = @@(t,y) [y(2); (1 - y(1)^2) * y(2) - y(1)]; ## ## opt = odeset ("OutputFcn", @@odeplot, "RelTol", 1e-6); ## sol = ode45 (fvdp, [0 20], [2 0], opt); ## @end group ## @end example ## ## Background Information: ## This function is called by an ode solver function if it was specified in ## the @qcode{"OutputFcn"} property of an options structure created with ## @code{odeset}. The ode solver will initially call the function with the ## syntax @code{odeplot ([@var{tfirst}, @var{tlast}], @var{y0}, "init")}. The ## function initializes internal variables, creates a new figure window, and ## sets the x limits of the plot. Subsequently, at each time step during the ## integration the ode solver calls @code{odeplot (@var{t}, @var{y}, [])}. ## At the end of the solution the ode solver calls ## @code{odeplot ([], [], "done")} so that odeplot can perform any clean-up ## actions required. ## @seealso{odeset, odeget, ode23, ode45} ## @end deftypefn function stop_solve = odeplot (t, y, flag) ## No input argument checking is done for better performance persistent hlines num_lines told yold; ## odeplot never stops the integration stop_solve = false; if (isempty (flag)) ## Default case, plot and return a value told = [told; t(:)]; yold = [yold, y]; for i = 1:num_lines set (hlines(i), "xdata", told, "ydata", yold(i,:)); endfor drawnow (); retval = false; elseif (strcmp (flag, "init")) ## t is either the time slot [tstart tstop] or [t0, t1, ..., tn] ## y is the initial value vector for the ode solution told = t(1); yold = y(:); figure (); hlines = plot (told, yold, "o-"); xlim ([t(1), t(end)]); # Fix limits which also speeds up plotting num_lines = numel (hlines); elseif (strcmp (flag, "done")) ## Cleanup after ode solver has finished. hlines = num_lines = told = yold = []; endif endfunction %!demo %! ## Solve an anonymous implementation of the Van der Pol equation %! ## and display the results while solving %! fvdp = @(t,y) [y(2); (1 - y(1)^2) * y(2) - y(1)]; %! opt = odeset ("RelTol", 1e-6); %! ode45 (fvdp, [0 20], [2 0], opt); %!demo %! ## Demonstrate simple multi-curve plot from t = 0 to 2 using initial, %! ## intermediate, and terminating odeplot calling syntaxes. %! t = linspace(0,2,10); %! y = [0.2*t; -0.1*t.^2-1; sin(t)]; %! %! disp("Plot initial points\n"); %! odeplot ([0 2], y(:,1), "init"); %! title("Plot first time step"); %! pause(1.5); %! %! disp("Append single time step\n"); %! odeplot (t(2), y(:,2), []); %! title("Append second time step"); %! pause(1.5); %! %! disp("Append remaining time steps\n"); %! odeplot (t(3:end), y(:, 3:end), []); %! title("Plot all time steps"); %! pause(1.5); %! %! disp("Terminate odeplot\n"); %! odeplot ([], [], "done"); %! title("Plot complete");