#include "pitch.h"
float lowpass(x)
float x;
{
	float c= .00048175311;
	float a1= -1.89919924;
	float c1= -1.923248041;
	float d1= .985720370;
	float a2= -1.86607670;
	float c2= -1.90075003;
	float d2= .948444690;
	float a3= -1.66423461;
	float c3= -1.87516686;
	float d3= .896241023;
	float c4= -.930449120;
	float temp,y;
	static float w1=ZERO,w11=ZERO,w12=ZERO,w2=ZERO,w21=ZERO;
	static float w22=ZERO,w3=ZERO,w31=ZERO,w32=ZERO,w4=ZERO;
	static float w41=ZERO,w42=ZERO;
	
	w1=c*x-c1*w11-d1*w12;
	temp=w1+a1*w11+w12;
	w12=w11;
	w11=w1;
	w2=temp-c2*w21-d2*w22;
	temp=w2+a2*w21+w22;
	w22=w21;
	w21=w2;
	w3=temp-c3*w31-d3*w32;
	temp=w3+a3*w31+w32;
	w32=w31;
	w31=w3;
	w4=temp-c4*w41;
	y=w4+w41;
/* w42 set but not used in lowpass */
	w42=w41;
	w41=w4;
	return(y);
}