Mercurial > octave-libtiff
view scripts/ode/private/runge_kutta_45_dorpri.m @ 20634:80e630b37ba1
maint: Remove unnecessary 'v' prefix before variables in ODE m-files.
* ode_rk_interpolate.m: Deleted file.
* odepkg_event_handle.m: Deleted file.
* runge_kutta_interpolate.m: Renamed from ode_rk_interpolate.m. Remove 'v'
prefix on variables. Delete blank space at end of lines.
* ode_event_handler.m: Renamed from odepkg_event_handle.m. Remove 'v'
prefix on variables. Delete blank space at end of lines. Use 'evt' for
event rather than 'eve' in variable names. Use 'idx' rather than 'index'
in variable names.
* scripts/ode/module.mk: Add ode_event_handler.m and runge_kutta_interpolate.m
to build system.
* AbsRel_Norm.m, starting_stepsize.m, ode_struct_value_check.m, odeget.m,
odeset.m: Delete blank space at end of lines.
* integrate_adaptive, integrate_const.m, integrate_n_steps.m,
runge_kutta_45_dorpri.m:
Remove 'v' prefix on variable. Delete blank space at end of lines.
* ode45.m: Expand docstring to cover more of the inputs/outputs.
Remove 'v' prefix on variable. Use name of variable in input validation
warnings. Use name of function as prefix in warnings and error messages.
Delete long, unnecessary comments. Use faster 'isempty' rather than slow
'isequal' to check whether option has been set. Remove SubOpts variable.
Shorten lines < 80 chars.
author | Rik <rik@octave.org> |
---|---|
date | Sun, 18 Oct 2015 09:55:41 -0700 |
parents | b92f8e148936 |
children | 516bb87ea72e |
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## Copyright (C) 2015 Carlo de Falco ## Copyright (C) 2013 Roberto Porcu' <roberto.porcu@polimi.it> ## ## 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 ## <http://www.gnu.org/licenses/>. ## -*- texinfo -*- ## @deftypefn {Function File} {[@var{t_next}, @var{x_next}] =} runge_kutta_45_dorpri (@var{@@fun}, @var{t}, @var{x}, @var{dt}, @var{options}, @var{k_vals_in}) ## @deftypefnx {Function File} {[@var{t_next}, @var{x_next}, @var{x_est}] =} runge_kutta_45_dorpri (@var{@@fun}, @var{t}, @var{x}, @var{dt}, @var{options}, @var{k_vals_in}) ## @deftypefnx {Function File} {[@var{t_next}, @var{x_next}, @var{x_est}, @var{k_vals_out}] =} runge_kutta_45_dorpri (@var{@@fun}, @var{t}, @var{x}, @var{dt}, @var{options}, @var{k_vals_in}) ## ## This function can be used to integrate a system of ODEs with a given initial ## condition @var{x} from @var{t} to @var{t+dt} with the Dormand-Prince method. ## For the definition of this method see ## @url{http://en.wikipedia.org/wiki/Dormand%E2%80%93Prince_method}. ## ## First output argument is the final integration time value. ## ## Second output parameter is the higher order computed solution at time ## @var{t_next} (local extrapolation). ## ## Third output parameter is a lower order solution for the estimation of the ## error. ## ## Fourth output parameter is matrix containing the Runge-Kutta evaluations ## to use in an FSAL scheme or for dense output. ## ## First input argument is the function describing the system of ODEs to be ## integrated. ## ## Second input parameter is the first extreme of integration interval. ## ## Third input argument is the initial condition of the system. ## ## Fourth input argument is the timestep, that is the length of the ## integration interval. ## ## Fifth input parameter is optional and describes a set of options useful to ## adapt the computation to what is needed. ## ## Sixth input parameter is optional and describes the Runge-Kutta evaluations ## of the previous step to use in an FSAL scheme. ## @end deftypefn ## ## @seealso{odepkg} function [t_next, x_next, x_est, k] = runge_kutta_45_dorpri (f, t, x, dt, options = [], k_vals = [], t_next = t + dt) persistent a = [0 0 0 0 0 0; 1/5 0 0 0 0 0; 3/40 9/40 0 0 0 0; 44/45 -56/15 32/9 0 0 0; 19372/6561 -25360/2187 64448/6561 -212/729 0 0; 9017/3168 -355/33 46732/5247 49/176 -5103/18656 0; 35/384 0 500/1113 125/192 -2187/6784 11/84]; persistent b = [0 1/5 3/10 4/5 8/9 1 1]; persistent c = [(35/384) 0 (500/1113) (125/192) (-2187/6784) (11/84)]; persistent c_prime = [(5179/57600) 0 (7571/16695) (393/640), ... (-92097/339200) (187/2100) (1/40)]; ## According to Shampine 1986: ## persistent c_prime = [(1951/21600) 0 (22642/50085) (451/720), ... ## (-12231/42400) (649/6300) (1/60)]; s = t + dt * b; cc = dt * c; aa = dt * a; k = zeros (rows (x), 7); if (! isempty (options)) # extra arguments for function evaluator args = options.funarguments; else args = {}; endif if (! isempty (k_vals)) # k values from previous step are passed k(:,1) = k_vals(:,end); # FSAL property else k(:,1) = feval (f, t, x, args{:}); endif k(:,2) = feval (f, s(2), x + k(:,1) * aa(2, 1).' , args{:}); k(:,3) = feval (f, s(3), x + k(:,1:2) * aa(3, 1:2).', args{:}); k(:,4) = feval (f, s(4), x + k(:,1:3) * aa(4, 1:3).', args{:}); k(:,5) = feval (f, s(5), x + k(:,1:4) * aa(5, 1:4).', args{:}); k(:,6) = feval (f, s(6), x + k(:,1:5) * aa(6, 1:5).', args{:}); ## compute new time and new values for the unknowns ## t_next = t + dt; x_next = x + k(:,1:6) * cc(:); # 5th order approximation ## if the estimation of the error is required if (nargout >= 3) ## new solution to be compared with the previous one k(:,7) = feval (f, t_next, x_next, args{:}); cc_prime = dt * c_prime; x_est = x + k * cc_prime(:); endif endfunction