T.D. Telford on Wed, 01 Apr 2020 22:00:09 +0200


[Date Prev] [Date Next] [Thread Prev] [Thread Next] [Date Index] [Thread Index]

Factoring and memory usage by matkermod


Hello,

I have written a MPQS factoring program, and GP was very useful.

To find the kernel of my smooth number exponents matrix (modulo 2 entries) m1, I used

matkermod (m1,2)

This works great for smaller dimensions of m1, but once m1 dimensions get to be about 1000, there appear to be memory usage problems.

For a large m1 (1000 x 1000), the stack size is < 100MB before calling matkermod, but matkermod wants to increase the size to 4000MB.

For a slightly larger m1, the stack size goes up to 8000MB.  Since I have 16 GB of memory, this limits how large a number I can factor.

I tried using gaussian elimination and finding the kernel, but the elimination is quite slow  (takes about the same time as all of the sieving).

So my questions are:

1. Is the large stack size increase by matkermod correct?
2. Can you suggest an alternate approach to finding the kernel?

Regards,
Doug