Optimizing the Particle Life: From 400 to 4M particles(programmingattack.com)

    #include <stdio.h>
    #include <stdlib.h>

    float mul_as_float(float t) {
      t += 0.02f * (float)17;
      return t;
    }

    float mul_as_double(float t) {
      t += (double)0.02f * (float)17;
      return t;
    }

    int main() {
        while (1) {
            unsigned r = rand();
            float t = *((float*)&r);

            float result1 = mul_as_float(t);
            float result2 = mul_as_double(t);
            if (result1 != result2) {
                printf("Counter example when t is %f (0x%x)\n", t, *((unsigned*)&t));
                printf("result1 is %f (0x%x)\n", result1, *((unsigned*)&result1));
                printf("result2 is %f (0x%x)\n", result2, *((unsigned*)&result2));
                return 0;
            }
        }
    }

    Counter example when t is 0.000000 (0x3477d43f)
    result1 is 0.340000 (0x3eae1483)
    result2 is 0.340000 (0x3eae1482)