[Patch,Fortran] PR 33197 Add NORM2 and PARITY

[Toon Moene]

Tobias Schlüter wrote:

> On 2010-08-26 15:39, Tobias Burnus wrote:
> 
>> For norm2 (L2 norm), one essentially does:
>> tmp = max(array) ! = L_infinity norm
>> norm2 = tmp * sqrt( (array/tmp)**2)
>> to avoid an overflow.

> Just a random idea: the maximum precision that such a single pass 
> algorithm can achieve is probably obtained by using and modifying the 
> binary exponent instead of multiplying with a scale factor as this 
> renders the scale transformations exact.

That's what people told me to do for quick complex divide in the '90s - 
however, at that time there were multiple supported floating point 
formats, so it was not *that* simple.

If IEEE-754 format is the only one supported now, that might be doable.

Cheers,

-- 
Toon Moene - e-mail: toon@moene.org - phone: +31 346 214290
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