float evp(nsample,f1,f2,q)
long nsample;
float *f1,*f2,*q;
{
	register jloc;
	float far = (float)(nsample)/ *q;
	if( far > *(q+1)) {
		jloc = (1. - ((far - *(q+1))/ *(q+4))) * *(q+3);
		return(*(f2+jloc));
		}
	else
		if(far >= *(q+2)) return(1.);
	else	{
		jloc = far * *(q+3)/ *(q+2);
		return(*(f1+jloc));
		}
}