References : Posted by Stefan Stenzel
Very hacked, but it gives a rough estimate of x**4 by modifying exponent and mantissa.
float p4fast(float in)
l-=0x3F800000l; /* un-bias */
l<<=2; /* **4 */
l+=0x3F800000l; /* bias */
/* compiler will read this from memory since & operator had been used */