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Old 2019-06-19, 17:55   #15
kriesel's Avatar
Mar 2017
US midwest

2·3·1,229 Posts
Default gpuowl residue type etc versus version

There are several PRP residue types. (See For the res64 to match between two primality tests of the same exponent, the residue types must match, unless perhaps the corresponding mersenne number is prime. (The residues would still not match, if the mersenne number was prime, if one primality test was PRP3 and the other PRP-1)
The PRP residue type(s) supported vary by gpuowl version.
If attempting to double check an existing primality test made by prime95 or other software, a correct gpuowl version must be used to match the residue type of the first test.

Early versions (up through v0.6) implemented the Lucas-Lehmer test instead.

A table of residue type(s) versus gpuowl version and some additional info follows in the pdf attachment.
In a nutshell: If you want a versatile selection of fft lengths and PRP type 4 residues, choose from v4.3 to v6.5-f34ad18. If you want PRP type 1 residues, choose from v6.5-84-30c0508 and more recent, or possibly if they're faster and have suitable fft lengths, v1.1-v3.9.
Available fft lengths versus gpuowl versions are listed at and some of these also indicate maximum exponent per fft length.

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File Type: pdf gpuowl versions and residue types.pdf (13.7 KB, 389 views)

Last fiddled with by kriesel on 2020-04-02 at 18:44 Reason: updated/expanded table, added LL early versions; added v6.5 type 1 commit
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