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Subject: Re: [boost] Review request: extended complex number library
From: Matthieu Schaller (matthieu.schaller_at_[hidden])
Date: 2012-03-09 11:54:21

>>> IIUC the standard cover just complex on builtin types, isn't it? See
>>> the C99 or C11 standards, annex G.
>>>> It also comes with a possible implementation.
>>> I don't which can be the correct implementation for C++ complex on
>>> builtin types without using arbitrary precision.
>>> I have no access to this standard. Please could you add it here?
>> look for instance n1124.pdf which is a C99 draft.
>> The aim is not to have full precision but to minimize
>> overflows/underflows and to
>> get good behviour with inf and nan.
>> For example
>> 1) (0+0i)*(inf+0i) must return nan+0i, not nan+nani
>> 2) if modulus(a)² overflow this must not necesseraly implies
>> that 1/a which is mathematically conj(a)/modulus(a)² underflows
> Thanks. I see now what you mean. I agree, correctness is important.

The question is thus do we (you) rather want a library that reproduces
the std::complex (i.e. the gcc and icc ones at least) class both in
terms of performance and accuracy or do we want a library that is more
accurate when de-normalized numbers are involved but that would be
slower than the standard one ?

I am not sure people would easily give up the speed of the standard one
just to be able to handle numbers that should anyway never enter
everyday calculations. What is your opinion ?

Matthieu Schaller

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