[PYTHON MATRIX-SIG] floating point handling

P. Dubois dubois@kristen.llnl.gov
Thu, 2 Nov 1995 09:57:44 +0800


(1) I disagree with Konrad's remarks on floating point.

I know of no production code that allows the generation of NaNs or any
of the other IEEE nonsense. If such a thing occurs in one of our codes 
it is an error and we need to hear about it immediately. Knowing *where*
the problem first occurred is crucial.

We use whatever facilities are provided on a given platform (and sometimes
there aren't any) to make sure that:

a. Any floating point problems signal FPE (which we then catch), except:
b. Fast-underflow-to-zero is turned on (Can make a real speed difference:
   if you don't do something about it, underflows result in system calls.)

There is no standardization in this area.

(2) I will supply a module that is equivalent to the Cray random number
generator. Stand by.




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