Re: [Bug-gsl] Bug in GFSR4 RNG code

[Brian Gough]

address@hidden writes:
 > I found a couple of errors in the code for the four-tap
 > shift-register-sequence random number generator (gfsr4.c) in the gsl-1.3
 > distribution.  I am attaching the corrected code.

Thanks for the bug report.

I've looked at the changes and I think the output of the existing
generator should be ok, although I agree it would be better to make it
consistent with r250.

I will change it in version 2.0, so that people don't get different
results from the generator when upgrading to 1.4.

If there's a problem with the actual randomness though do let me know.

best regards,

-- 
Brian Gough

Network Theory Ltd            
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Bristol BS8 3AL               
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$ diff gfsr4.c ~/tmp/gfsr4_new.c 
127a142
>   state->nd = i-1;
133,134c148,149
<   for (i=0; i<32; ++i) {
<       int k=7+i*3;
---
>   for (i=0; i<32; i++) {
>       int k=7*i+3;
141d155
<   state->nd = i;