Mercurial > octave
view scripts/ode/private/kahan.m @ 20621:b92f8e148936
maint: Continued clean-up of functions in ode/private dir.
* AbsRel_Norm.m: Use retval as return variable. Use sumsq() rather than explicit
squaring of vector and sum(). Combine multiple lines where possible.
* integrate_adaptive.m: Rewrite docstring. Only call starting_stepsize() if
InitialStep option is empty.
* integrate_const.m: Rewrite docstring. Remove useless commented out code.
Combine multiple lines where possible.
* integrate_n_steps.m: Rewrite docstring. Remove useless commented out code.
Combine multiple lines where possible.
* kahan.m: Remove excessive 4-space indentation, use 2-space indentation.
* ode_rk_interpolate.m: Use parentheses around condition for switch stmt.
Combine multiple lines where possible.
* ode_struct_value_check.m: Remove comma from Copyright statement that Octave
doesn't use.
* odepkg_event_handle.m: Remove comma from Copyright statement that Octave
doesn't use.
* odepkg_structure_check.m: Remove comma from Copyright statement that Octave
doesn't use.
* runge_kutta_45_dorpri.m: Remove comma from Copyright statement that Octave
doesn't use. Improve docstring. Match variable names in documentation to
those in code.
* starting_stepsize.m: Rewrite docstring. Use spaces between function name
and opening parenthesis.
author | Rik <rik@octave.org> |
---|---|
date | Wed, 14 Oct 2015 10:35:53 -0700 |
parents | eb9e2d187ed2 |
children | 80e630b37ba1 |
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## 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{sum} =} kahan (@var{sum}, @var{comp}, @var{term}) ## @deftypefnx {Function File} {[@var{sum}, @var{comp}] =} kahan (@var{sum}, @var{comp}, @var{term}) ## ## This function implements the Kahan summation algorithm, also known as ## compensated summation. ## ## The algorithm significantly reduces the numerical error in the total ## obtained by adding a sequence of finite precision floating point numbers, ## compared to the straightforward approach. For more details ## see @url{http://en.wikipedia.org/wiki/Kahan_summation_algorithm}. ## This function is called by @command{integrate_adaptive} and ## @command{integrate_const} to better catch equality comparisons. ## ## The first input argument is the variable that will contain the summation, ## so that is also returned as first output argument in order to reuse it in ## next calls to @code{kahan} function. ## ## The second input argument contains the compensation term and it is returned ## as the second output argument so that it can be reused in future calls of ## the same summation. ## ## The third input argument @var{term} is the variable to be added to @var{sum}. ## @end deftypefn function [sum, comp] = kahan (sum, comp, term) y = term - comp; t = sum + y; comp = (t - sum) - y; sum = t; endfunction