laxwen1.c++

来自「卡尔曼滤波类」· C++ 代码 · 共 51 行

// laxwen1.cpp		implementation of 1-D single step Lax-Wendroff

#include <laxwen1.hpp>

float null_rhs(Vector&, int)
{
	return 0;
}

LaxWendroff1::LaxWendroff1(SpaceDeriv fin, float dxin, float dtin, int ni,
			 SpaceDeriv user_rhs) : f(fin),
			Dynamics(ni,dtin,"Single-step Lax-Wendroff")
{

	u_new.resize(n);

	r = dt / dxin;
	
        if ( user_rhs == NULL )
		rhs = null_rhs;
	else
		rhs = user_rhs;

}

void LaxWendroff1::step(const int steps)
{
	int it, j, jm, jp;

	for (it = 0; it < steps; it++)
	{
		for (j = 0; j < n; j++)
		{
			jp = j + 1;
			if ( jp >= n )
				jp -= n;
			jm = j - 1;
			if ( jm < 0 )
				jm += n;
			u_new[j] = u[j] - 0.5 * r * (f(u,jp) - f(u,jm))
				      + 0.5 * r * r * (f(u,jp) - 2 *
						f(u,j) + f(u,jm) )
					+ dt * rhs(u,j);
	
		}
                u = u_new;
	}
	
}