Talk:Linear congruential generator: Difference between revisions
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:::: Some implementations may need to address this. That's also why having a common example sequence (with an overflow) is needed. --[[User:Dgamey|Dgamey]] 03:13, 12 July 2011 (UTC) |
:::: Some implementations may need to address this. That's also why having a common example sequence (with an overflow) is needed. --[[User:Dgamey|Dgamey]] 03:13, 12 July 2011 (UTC) |
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::::: Are you sure? If your integer is at least 32 bit long (shorter obviously won't do), sign bit has an impact only on the sign of modulo operator. Using 64 bits, no overflow can occur and the sequence is 12345, 1406932606..., you did something wrong with your second series. Also, if you use 32 bit signed integer, 2**31 is going to be negative. If you use modulo operator you may get a negative random number which is pretty obviously wrong, but if your language convention always returns a positive one, then it's actually correct. Largely there's no subtle error in this method, overflow or not. (Should clarify: above is assuming fixed length, 2's compliment binary integer representation. It's clearly not a problem if you have arbitrary precision integers) --[[User:Ledrug|Ledrug]] 03:33, 12 July 2011 (UTC) |
::::: Are you sure? If your integer is at least 32 bit long (shorter obviously won't do), sign bit has an impact only on the sign of modulo operator. Using 64 bits, no overflow can occur and the sequence is 12345, 1406932606..., you did something wrong with your second series. Also, if you use 32 bit signed integer, 2**31 is going to be negative. If you use modulo operator you may get a negative random number which is pretty obviously wrong, but if your language convention always returns a positive one, then it's actually correct. Largely there's no subtle error in this method, overflow or not. (Should clarify: above is assuming fixed length, 2's compliment binary integer representation. It's clearly not a problem if you have arbitrary precision integers) --[[User:Ledrug|Ledrug]] 03:33, 12 July 2011 (UTC) |
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:::::: Ooops, Seems I am cross-eyed. Had it in my head as 2^31-1 modulus (a couple of other historical LCRNG .... --[[User:Dgamey|Dgamey]] 03:47, 12 July 2011 (UTC) |
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