FFT functions

[Paul Underwood]

Hi,

we are developing a cubic Frobenius test (that rivals mpz_probab_prime#_p): https://github.com/Boutoukoat/CubicPrimalityTest

We have to calculate s^2, t^2, u^2, 2*s*t, 2*t*u and 2*u*s which currently we do with 6 squarings. After some manipulations we do 3 mod reductions.

GMP works fantastically. Thanks team!

Our question is will the GMP team ever provide FFT functions:
* forward_FFT
* pointwise_mult
* reverse_FFT
?

We would then be able to do 3 forward transforms, 6 point-wise ops and 6 inverse transforms.

Best Wishes

Paul