Pow(x,4) approximation¶
- Author or source: Stefan Stenzel
- Created: 2002-01-17 03:09:20
Very hacked, but it gives a rough estimate of x**4 by modifying exponent and mantissa.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | float p4fast(float in)
{
long *lp,l;
lp=(long *)(&in);
l=*lp;
l-=0x3F800000l; /* un-bias */
l<<=2; /* **4 */
l+=0x3F800000l; /* bias */
*lp=l;
/* compiler will read this from memory since & operator had been used */
return in;
}
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