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## [Discuss-gnuradio] gr_noise_source_X( ) only negative seeds?

**From**: |
Tim Meehan |

**Subject**: |
[Discuss-gnuradio] gr_noise_source_X( ) only negative seeds? |

**Date**: |
Thu, 8 Mar 2007 16:06:35 -0800 |

Hi All
When seeded with a positive number gr_noise_source_X seems to always
return the same sequence.
i.e.
call gr_noise_source_f(gr.GAUSSIAN,1,Z) where Z > 0 the sequence is
always the same. Called with a negative seed (Z < 0 ) it behaves as I
would expect.
Am I missing something?
I think this is from lines below in gr_random, but the comment
made me scared to touch it :-)
/*
* This looks like it returns a uniform random deviate between 0.0 and 1.0
* It looks similar to code from "Numerical Recipes in C".
*/
float gr_random::ran1()
{
int j;
long k;
float temp;
if (d_seed <= 0 || !d_iy) {
if (-d_seed < 1) <<<<<<<<<< HERE
d_seed=1; <<<<<<<<<< and HERE
else
d_seed = -d_seed;
for (j=NTAB+7;j>=0;j--) {
k=d_seed/IQ;
<snip>

**[Discuss-gnuradio] gr_noise_source_X( ) only negative seeds?**,
*Tim Meehan* **<=**