I suggest that instead of the intrinsic random number generators
provided by the two compilers, you use the same external generator
in both cases. There are some good ones, see for instance:
http://www.honeylocust.com/RngPack/doc/edu.cornell.lassp.houle.RngPack.Ranmar.html
Intrinsic random number generators have never had a very good reputation
anyway, at least in the past. Has anybody done some tests about those
available in Fortran 90 compilers?
Alberto Fasso'
On Tue, 28 Mar 2000, Hjalmarson, Harold P. wrote:
> Hello,
>
> For a certain Fortran 90 calculation I get very different results depending
> on whether I use Sun Workshop 4.2 or 5.0. The 4.2 results seem to be
> correct, and they agree with results using a DEC computer.
>
> The calculation is a Monte Carlo solution of the Boltzmann equation for
> electric field driven transport in GaAs.
>
> I suspect that the error may arise in the intrinsic random number generator
> random_number. Perhaps it is implemented differently in Workshop 4.2 and
> 5.0? However, I don't see why a different implementation would cause the
> large effects I see in the final results.
>
> All of my source code is identical for these two calculations.
>
> Any comments about known problems would be much appreciated because it can
> be difficult to compare "identical" probabilistic calculations.
>
> Meanwhile I will look into reviving some code that I used long ago to test
> random number generators.
>
> Harry
>
> ---
> Harold P. Hjalmarson
> (Materials Simulation Sciences, Dept. 9225)
> Sandia National Labs, MS-1111, PO Box 5800, Albuquerque, NM 87185-1111
> [log in to unmask] (Internet) 505-844-8888 (office) 505-845-7442 (fax)
--------------------------------------------------
Alberto Fasso'
Stanford Linear Accelerator Center
Radiation Physics Dept. ms 48
2575 Sand Hill Road
Menlo Park, CA 94025
Tel. (1 650) 926 4062 Fax: (1 650) 926 3569
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