topic Re: different random number each time in Intel® Fortran Compiler

different random number each time

csliu — Tue, 26 Aug 2003 00:17:17 GMT

I read the topic about random number posted previously.
As the Fortran's help files said, I referred RND$TIMESEED as the argument of the seed, I can get the different random number seqences each time.

PROGRAM temp
USE DFLIB
REAL rand
CALL SEED(RND$TIMESEED)
CALL RANDOM(rand)
print *, "random =", rand
END PROGRAM temp

Now, I meet the new problem
How can I get diffent seed for other random number generator each time, like ran2(idum) in Numerical Recipes in Fortran?

Re: different random number each time

TimP — Tue, 26 Aug 2003 07:10:03 GMT

The usual method for getting different sequences from RNG code, where source is provided, is to set the seed(s) from contents of the DATE_AND_TIME VALUES array, elements (5:8). Looks like that could be consistent. However, you might use RANDOM_SEED() and RANDOM_NUMBER(). The usual reason for using the Numerical Recipes functions would be to get the same sequences on different compilers, or possibly a quicker but less rigorous sequence than Fortran's own library.

Re: different random number each time

kdkeefer — Tue, 26 Aug 2003 23:12:02 GMT

Tim,
FYI, the authors of NR for Fortran, 2nd Ed. offer a $1000 reward for anyone who can demonstrate that RAN2 fails any test in a non-trivial way :).
Keith