#include "math.h"
  #include "3rnd1.c"
  double mtcl(a,b,f)
  double a,b,(*f)();
  { int m;
    double r,d,x,s;
    r=1.0; s=0.0; d=10000.0;
    for (m=0; m<=9999; m++)
      { x=a+(b-a)*rnd1(&r);
        s=s+(*f)(x)/d;
      }
    s=s*(b-a);
    return(s);
  }