初学SAS,一下程序是求积分，请问错误在哪/,多谢多谢...

PROC IML;
    start integrand1(x) global(y,rho);
        val1 = log(1+y-2*sqrt(y)*cos(x)+y*rho)*4*y*(sin(x))**2;
        val2 = 2*pi*y*(1+y-2*sqrt(y)*cos(x));
        val3 = val1/val2;
        return(val3);
    finish;

    p = 500;
    n = 300;
    y = n/p;
    rho = 4;
    interval = 0 || pi;
    call quad(M,"integrand1",interval);
    print M;

The function "integrand1" is the integrand function with two global variables.