PI2
x=drem(x,PI2); /* reduce x into [-PI,PI] */
x=drem(x,PI2); /* reduce x into [-PI,PI] */
vc(PI2, 6.2831853071795864540E0 ,0fda,41c9,68c2,a221, 3, .C90FDAA22168C2)
ic(PI2, 6.2831853071795862320E0 , 2, 1.921FB54442D18)
#define PI2 vccast(PI2)
sin(i * PI2 * (freq1 / sample_rate)) +
sin(i * PI2 * (freq2 / sample_rate))