Saving the current seed in a Fortran random number sequence

Question

I am currently using the intrinsic function rand() to generate random numbers. I initialized my sequence with some defined seed, but I want to be able to output the current seed that rand() is using at some point in my loop.

By doing this, I should be able to "continue" the sequence of random numbers in a new program.

From what I have seen online, there is no way to do this with the random number generator associated with rand() and srand() functions. Is this true? Can anyone suggest a different method (perhaps, RANDOM_NUMBER()?).

Answer 1

rand and srand are not standard Fortran functions. I expect your compiler documentation can tell you how best to use them. However the Fortran standard defines a subroutine random_seed with three optional arguments (named save, put and get). put and get are for setting and getting the random seed. save can be used to return the size of integer array used to hold the seed for the PRNG. The generator can then be called with the standard routine random_number.