vector_up(equation,ivar,idim,low_vector,vector)
float equation[], low_vector[],vector[];
int ivar, idim;
{
	int i;

	vector[ivar] = 0.0;
	for(i=0; i<ivar; i++) {
		vector[i] = low_vector[i];
		vector[ivar] -= equation[i]*low_vector[i];
	}
	for(i=ivar+1; i<=idim; i++) {
		vector[i] = low_vector[i-1];
		vector[ivar] -= equation[i]*low_vector[i-1];
	}
	vector[ivar] /= equation[ivar];
}