Talk:Pernicious numbers: Difference between revisions

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rosettacode>Gerard Schildberger

Revision as of 14:43, 12 March 2014 (view source) Grondilu (talk \| contribs) (About the C solution)		Latest revision as of 20:16, 12 March 2014 (view source) rosettacode>Gerard Schildberger m (→‎Wiki link removal: added a comment about underscoring links.)
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Line 1: ==C solution too cryptic?== Hi, the C solution is a bit mysterious to me. The for loop seems to "remove the zeros" asif I understand correctly, but then what's so special about 2693408940 ?? How can a simple bitwise & tell if the number of 1 (which is now the length since all zeros have been removed) is prime? A bit of explanation in the introduction of the section or in comment would be welcome--[[User:Grondilu\|Grondilu]] ([[User talk:Grondilu\|talk]]) 14:43, 12 March 2014 (UTC) :Edit, hum after some analysis it appears that 2693408940 encodes the prime numbers in its binary form: 10100000100010100010100010101100. From right to left, starting from 0, the one marks the primes. Sill this could use some explanations.--[[User:Grondilu\|Grondilu]] ([[User talk:Grondilu\|talk]]) 14:51, 12 March 2014 (UTC) :OK, I understand now. I added some comments in the code. Hope it's ok.--[[User:Grondilu\|Grondilu]] ([[User talk:Grondilu\|talk]]) 15:02, 12 March 2014 (UTC) :: Er yeah, it was pretty cryptic, and your analysis is absolutely correct. But I changed the routine again for something faster, though I did put in some comments this time. I didn't retain the "0b010011..." literal format since it's a GCC exteinsion, but if you want it back in I'm not really troubled by it. --[[User:Ledrug\|Ledrug]] ([[User talk:Ledrug\|talk]]) 19:40, 12 March 2014 (UTC) ==Wiki link removal== Why was the Wikipedia link removed (for Pernicious number) ? -- [[User:Gerard Schildberger\|Gerard Schildberger]] ([[User talk:Gerard Schildberger\|talk]]) 20:00, 12 March 2014 (UTC) The "hidden link" to Wiki's link within the definition of ''pernicious number'' isn't obvious unless one hovers over it and then Rosetta Code then underlines/underscores it, indicating that it's a link (either that, or my eyes are getting really bad).   I can't see the harm on having an explicit link listed with the others. -- [[User:Gerard Schildberger\|Gerard Schildberger]] ([[User talk:Gerard Schildberger\|talk]]) 20:16, 12 March 2014 (UTC)