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From: Jens Maurer (Jens.Maurer_at_[hidden])
Date: 20010911 14:54:48
"Paul A. Bristow" wrote:
> Attached is a tranlsation of ACM TOMS 715.f ANORM into C++.
> It does the normal distribution function.
> (NOT yet Boostified before anyone comments!)
>
> (prob.cpp is the function, prob.h just declares it, test.cpp
> and its results in a .txt file (also pasted into the prob.cpp
> at the end)
I'd expect that the case
if (x > 8.572)
should return 1, not 0.
The normal distribution is defined for all (real) arguments
x, therefore its domain is easy.
> I see no reason why an exception should be raised if the argument falls
> outside the values, as the value 0 or 1 should be returned.
Yes, the function is mathematically defined for all (real)
arguments. An IEEEaware implementation should probably check
for x == NaN and shortcircuit that case.
> Cody says:
>
> C Error returns
> C The program returns ANORM = 0 for ARG .LE. XLOW.
Not an error, just a normal result.
> but I don't see (as a mad scientist and not a mad mathematican)
> why this is an error or needs flagging, except that the result
> might be denormalised
What's wrong with the result being denormalized?
Jens Maurer
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