NTL 10.2.0

[Victor Shoup]

Just posted a new version. In addition to a few performance improvements, 

I've added new routines that give direct access to the underlying "limbs" of a ZZ,

which is a feature that has been requested from time to time.

As usual, go to: http://www.shoup.net/ntl

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The next thing I will be working on is implementing a multi-modular algorithm

for matrix multiplication over ZZ_p, using the now much faster matrix multiplication

algorithms over zz_p.  My preliminary estimates indicate that this should 

speed up NTL's mat_ZZ_p mul routines by a factor of 10-20x.

And a multicore version should make it even faster.

After I get faster matrix multiplication working, I want to first experiment with

applying it to the modular composition algorithm used in the ZZ_pX factoring

algorithm.  I'm hoping to get a 2-3x speedup in the DDF routine.

After that, I want to work on implementing the reductions from matrix inversion, etc,

to matrix multiplication (over ZZ_p). For this I can probably "re-purpose" FLINT or other

open-source code that has already been written.  If anyone would like to help me

with that, I would be grateful.

This multi-modular approach to matrix mul is of course not new --- it is in Sage already

via FFLAS, I think.  But still, I'd like to work on getting a fairly decent implementation in NTL.

It's a hobby :-)

Note: Based on my benchmarks, for 20-bit primes, NTL's mat_zz_p multiplication

is about 20% slower than FFLAS on an x86 with AVX2, so not too bad.

Also, NTL's inversion routine is a bit faster than FFLAS's (between 15-35%).

[Bill Hart]

If there's anything specific I can do to help, just let me know.