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Old 2014-11-26, 20:47   #5
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Apr 2003
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Now that the computation of the modular inverse is correct, I can release the code as a beta. The factors that are found all appear to be valid. I have a hacked version of pfgw that can take the .log file and verify the factors in it. I need to release that soon.

Here is an example of what you might see when it runs, in this case on an Intel HD Graphics 4000. Note that I fixed that first string of output. I just didn't fix it in what I attached.

gcwsievecl64 -v -C -W -b200 -B201 -n2 -t2 -N1e5 -P1e6
gcwsievecl v1.0.1, a GPU program to find factors numbers of the form k*b^n+c where k, b, and n are fixed
Quick elimination of terms info (in order of check):
    99998 because the term is even
    63411 because the term is divisible by a prime < 100
Platform 0 is an Intel(R) Corporation Intel(R) OpenCL, version OpenCL 1.1
Device 0 is an Intel(R) Corporation Intel(R) HD Graphics 4000
workGroupSize = 51200 = 200 * 16 * 16 (blocks * workGroupSizeMultiple * deviceComputeUnits)
Running with 2 threads
Allocated memory (prior to sieving):  315 MB in CPU, 82 MB in GPU
Sieve started: (cmdline) 0 <= p < 1000000 with 36589 terms

Sieve complete: 3 <= p < 1000000  78498 primes tested
Clock time: 34.81 seconds at 2255 p/sec.  Factors found: 26031
Processor time: 39.89 sec. (5.46 init + 34.43 sieve).
Seconds spent in CPU and GPU: 13.41 (cpu), 35.72 (gpu)
Percent of time spent in CPU vs. GPU: 27.29 (cpu), 72.71 (gpu)
CPU/GPU utilization: 1.15 (cores), 1.00 (devices)
Started with 36589 terms and sieved to 1000000.  10558 remaining terms written to gcw_201.pfgw
Unlike gcwsieve, this program doesn't have restrictions on p (min p > max n). In fact, I could modify gcwsieve to remove that restriction as there is a little trick I used in this code to eliminate it, but if this program works correctly, I don't think that will be necessary.

I will be very curious to know how well this works and how fast (or slow) it is compared to gcwsieve on your systems.

Last fiddled with by rogue on 2020-09-24 at 19:47
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