• tsukikage <tsukikage dmail.com> Feb 12 2011
• Don <nospam nospam.com> Feb 18 2011

tsukikage <tsukikage dmail.com> writes:

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Please see source in attachment.
The output is

  M2 M3 M5 M7 M13 M17 M19 M31 M61 M89 M107 M127 M521 M607 M1279 M2203 M2281
M3217 M4253 M4423
*** M9689***
  M9941 M11213 M19937
*** M21701***
  M23209

It missed 2 Mersenne Primes 9689 & 21701.
Is it my program bug or bigint broken?
It seems subtle.

Thank you!

Don <nospam nospam.com> writes:

tsukikage wrote:
 Please see source in attachment.
 The output is
 
  M2 M3 M5 M7 M13 M17 M19 M31 M61 M89 M107 M127 M521 M607 M1279 M2203 
 M2281 M3217 M4253 M4423
 *** M9689***
  M9941 M11213 M19937
 *** M21701***
  M23209
 
 It missed 2 Mersenne Primes 9689 & 21701.
 Is it my program bug or bigint broken?
 It seems subtle.
 
 Thank you!
 


That's quite a terrible bug in Bigint. It's slipped through testing 
because of a fault in the win32 Phobos makefile (someone disabled 
asserts!). If Phobos is compiled in debug mode, your code causes an 
assert failure inside the bigint code.

It's a straightforward problem with the fast recursive division 
implementation, failing to properly normalize intermediate quotients.
Unfortunately the fix won't make the next release, which happens in a 
few hours.