before i present my and other approaches to RTCG, here's an example:

in graphics the power function is a good candidate for RTCG because when shading a surface power is called with a different base per pixel, but the exponent remains constant as it depends only the the surface properties.

double power(double base, int exp) {
   int t, bit = 1;
   int square = base;
   double result = 1.0;

   while (bit <= exp) {
      if (bit & exp)
	 result *= square;
      bit = bit << 1;
      square *= square;
   }
   return result;
}

the simplest implementation:

exponent = surface();
for (i = 0; i < bign; i++)
  ans[i] = power(exponent, base[i]);

exponent = surface();
p_e = power_gen(exponent);
for (i = 0; i < bign; i++)
  ans[i] = p_e(base[i]);