strange behaviour with gsl_cdf_fdist_Q()

[Rajarshi Guha <rajarshi at presidency dot com>]

Hi,
  more problems with gsl_cdf_fdist_Q() and very strange ones at that!

I'm using the above function in a program where a memory is alloced and
realloced multiple times. 

I edited the file fdist.c to print out values on entry and just before
exit and the values that I see are OK:

# x = 3.145724 nu1 = 3.000000 nu2 = 23.000000 P = 0.044555

However, the return value is weird!

double pf = 0.0;
...
pf = gsl_cdf_fdist_Q(3.145724,(double)3,(double)23);
printf("%f\n", pf);

gives me

13.00000

Furthermore, on the next iteration a struct is corrupted for some reason
(elements have values of nan).

I have run my program through valgrind and I have no memory errors or
leaks. I also checked it with ElectricFence and that gives my program a
clean bill.

I'm pretty sure its some form of memory corruption somewhere, but as far
as the tools above see, my code is clean. I understand that the problem
is probably in my program, but has anybody experienced anything like
this and if so did they find out what was going on?

I delved into fdist.c but it seems that any memory problems would come
from beta.c but I'm not sure.

Any suggestions would prevent me from going bald at an early age :)

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Rajarshi Guha <rajarshi@presidency.com> <http://jijo.cjb.net>
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Psychology is merely producing habits out of rats.