ni...@lysator.liu.se (Niels Möller) writes:
Sounds right. Such convolution type sum-of-products might want a
separate function, returning 3 limbs.
But I'm not talking about a convolution, but about the complete
powering. If x is a candidate nth root, and x^n is of size s bits, I
Torbjorn Granlund t...@gmplib.org writes:
I would like to avoid fp hardware in the portable parts of GMP.
I guess this means: Avoid using functions from libm, and avoid using
floating point in critical loops. Right? There's a (non-critical)
floating point operation in mpn_perfect_power_p
ni...@lysator.liu.se (Niels Möller) writes:
I guess this means: Avoid using functions from libm, and avoid using
floating point in critical loops. Right? There's a (non-critical)
floating point operation in mpn_perfect_power_p involving some logarithm
table.
Right. I would actually
Torbjorn Granlund t...@gmplib.org writes:
I just got a crazy idea. Compute the logarithm of the number (to a few
bits of precision, perhaps using table lookup). Multiply this logarithm
by k. Exponentiate using the logbase (again using a small table).
Conservatively compare to number being
ni...@lysator.liu.se (Niels Möller) writes:
Ah, and if we're brain storming, yet another variant would be to compute
an extra limb (or maybe only half a limb) of precision when we compute
the 2-adic k'th root. If the extra limb is non-zero, then the input can't
be a k'th power. That's
