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Use integers for ziggurat cutoff comparison #324

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richfitz opened this issue Nov 8, 2021 · 1 comment
Open

Use integers for ziggurat cutoff comparison #324

richfitz opened this issue Nov 8, 2021 · 1 comment

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@richfitz
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richfitz commented Nov 8, 2021

See Doornik and the wikipedia page; it's apparently faster to use a integer table of x[i] / x[i - 1] then compare the rng integer value against that. Requires that we keep two tables, one for uint32 and uint64 of course, and some benchmarking and explanation would be nice
@richfitz richfitz changed the title Use integers for cutoff comparison Use integers for ziggurat cutoff comparison Nov 8, 2021
This was referenced Nov 8, 2021
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@richfitz richfitz added this to the CRAN release (v1.0.x) milestone Nov 8, 2021
@richfitz
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This is going to be really hard as we can't easily get two versions of the coefficients for different integer types given the big fight in #327/#328; I still think it could be worth doing if faster but don't believe it will be that much faster...

@richfitz richfitz removed this from the CRAN release (v1.0.x) milestone Nov 15, 2021
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