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