In message <email@example.com>, Glen Low <firstname.lastname@example.org> writes
>I need a fast exponent and logarithm routine for floats. It should >preferably use only adds, subtracts and multiplies; divides and square >roots are permissible if necessary. It should not use large lookup >tables. An additional wrinkle (or help) is that there's a exponent and >a logarithm estimate available. (In case you're wondering, this is the >situation with the Altivec SIMD instruction set.)
Log(1+x) ~ x(6+x)/(6+4x)
Might be of some use depending on how fast your divide is (for small x)
You also need to specify how accurate the log(x) and exp(x) must be - fastest methods that cut corners for speed are not necessarily as accurate.