public class Test {

  // calculate product to 1000 terms
  static double product(double x) {
    double result = 1.0;
    double pi2 = Math.PI * Math.PI; // pi squared
    for (int n = 1; n < 1000; n++) {
      result *= (1 - x * x / (n * n * pi2));
    }
    return result;
  }

  public static void main(String[] args) {

    for (double x = 0.1; x<3; x+=0.1) // a range of x values, in radians
    {
    double lhs = Math.sin(x) / x;
    double rhs = product(x);
    System.out.printf("x = %8f, LHS = %8f, RHS = %8f \n",x,lhs,rhs);
    }

  }

}