Re: Random numbers in tasks

["Bobby D. Bryant" <bdbryant@mail.utexas.edu>]

On Mon, 02 Jun 2003 03:29:33 +0000, Robert I. Eachus wrote:

> Papastefanos Serafeim wrote:
>> There is a small problem in that solution, I cannot just declare the
>> generator in the task type: There is a function in a different package
>> that is used to return a random number in a given range and that
>> function is used at other places too...
> 
> There is magic in Ada for especially this purpose.  It is in Annex C, so
> it is possible that some compilers don't support it.  Look at C.7.2 The
> Package Task_Attributes.  Here is an example and output using GNAT.
> Notice that this version uses a fixed seed for each different task.  If
> you want different seeds for every run modify the body of
> My_Float_Random.Gen_Source.  But notice that just using a call to get
> seeds based on the clock may not be sufficient, unless you put a delay
> in.

FWIW, I have a GA solver with similar requirements, and I just have the
tasks rendezvous with a 'controller' task that dispenses individual seeds
for them to initialize on.  After that they can run independently.

-- 
Bobby Bryant
Austin, Texas