w_methods.c File Reference

This file implements the functions of the W Methods integrator in C. Warning : should be tested. More...

#include "integrator.h"
#include "MBSfun.h"
#include "mbs_message.h"
#include "mbs_dirdyn.h"
#include "mbs_dirdyn_struct.h"
#include "mbs_w_methods.h"
#include "useful_functions.h"
#include "nrfct.h"

Functions
int	w_methods (double y[], double dydx[], int n, double x, double h, double yout[], int(*derivs)(double, double[], double[], MbsData *, MbsDirdyn *), MbsData *s, MbsDirdyn *mbs_dd)
	W Methods integrator implementation. More...

Detailed Description

This file implements the functions of the W Methods integrator in C. Warning : should be tested.

Creation date: June 2018

Author

Sebastien Timmermans

@source Arnold M. et al, Linearly implicit time integration methods in real-time applications: DAEs and stiff ODEs Multibody System Dynamics, 2007, 17:99–117

(c) Universite catholique de Louvain

Function Documentation

w_methods()

int w_methods	(	double	y[],
		double	dydx[],
		int	n,
		double	x,
		double	h,
		double	yout[],
		int(*)(double, double[], double[], MbsData *, MbsDirdyn *)	derivs,
		MbsData *	s,
		MbsDirdyn *	mbs_dd
	)

W Methods integrator implementation.

@source (adapted from) Arnold M. et al, Linearly implicit time integration methods in real-time applications: DAEs and stiff ODEs Multibody System Dynamics, 2007, 17:99–117

Parameters

y	state vector of variable
dydx	derivative of y by x
n	number of variables
x	current time value, at which the function needs to be computed
h	time step
yout	solution of the incremented variables
derivs	the function computing f'
s	the MbsData structure of the model on which dirdyn analysis is computed.
mbs_dd	the MbsDirdyn structure related to the integration.

Returns

error_code Return a negative number if something went wrong, 0 otherwise

calls an external function

A = (- h* Jv - h*h * Jp )

A = ( I - * Jv - h * h * Jp)

add 1/h in diagonal terms (identity matrix)

partial

useless if s<2

sum alpha + gamma

Jp * Xv

Complete right-hand term B

B = f + h * Jp * Xv gamma +

delta p = Xv + h * delta v