#include <math.h>
#include <stdio.h>
int main(){
double x = -10;
double const dx=.01;
double s0 = 0, s2 = 0;
while(x < 10) {double y = exp(- x*x); s0 += y; s2 += x*x*y; x += dx;}
{double const i0 = s0*dx, i2 = s2*dx;
printf(
  "m0 = %20.16f,   m0*m0 = %20.16f\n"
  "m2 = %20.16f, 4*m2*m2 = %20.16f\n",
  i0, i0*i0, i2, 4*i2*i2);}
return 0;}
/* Output:
m0 =   1.7724538509055174,   m0*m0 =   3.1415926535897984
m2 =   0.8862269254527586, 4*m2*m2 =   3.1415926535897976
*/