strfry does not always give a uniform distribution

[Matt Turner]

On Fri, Sep 24, 2010 at 10:55 PM, Steve Ward <planet36@gmail.com> wrote:
> The strfry function does not always give a uniform distribution.  Run
> the attached program and you can see that (once every few tries)
> strfry is biased toward some permutations of the input string.  I
> modified strfry to not use a custom prng state.  It seems to behave
> much more fairly.
>
>
> Example output:
>
>
> DEFAULT_STR: ab
>
> max_iterations: 50000000
>
> getpid: 2862
>
> (1285379699) strfry...
> (1285379709) strfry_mod...
>
> strfry_histogram
> ab => 27952756  (55.9055%)
> ba => 22047244  (44.0945%)
>
> strfry_mod_histogram
> ab => 25002087  (50.0042%)
> ba => 24997913  (49.9958%)
>
>
>
> DEFAULT_STR: abc
>
> max_iterations: 25000000
>
> getpid: 3336
>
> (1285381555) strfry...
> (1285381561) strfry_mod...
>
> strfry_histogram
> abc => 3610465  (14.4419%)
> acb => 4723913  (18.8957%)
> bac => 3607390  (14.4296%)
> bca => 4726172  (18.9047%)
> cab => 4723147  (18.8926%)
> cba => 3608913  (14.4357%)
>
> strfry_mod_histogram
> abc => 4163372  (16.6535%)
> acb => 4165675  (16.6627%)
> bac => 4165102  (16.6604%)
> bca => 4170281  (16.6811%)
> cab => 4166255  (16.665%)
> cba => 4169315  (16.6773%)
>
>
>
> Steve Ward

Oh man, here we go.

http://sourceware.org/bugzilla/show_bug.cgi?id=4403