Hello world,
J3, the US Fortran standards committee, has passed
https://j3-fortran.org/doc/year/24/24-179.txt
which states (with a bit of an overabundance of
clarity) that, in Fortran, it is possible special-case
complex multiplication when one of the numbers is known
to have a zero component, for example when promoting
a real to complex for complex multiplication. For
example, multiplying a complex variable b with a real
variable a can be done with c%re = b%re * a, c%im = b%im * a,
without considering NaNs and infinities. Apparently, other
Fortran compilers do this.
They also stated that ISO/IEC 60559:2020 (aka IEEE 754) does
not specify complex arithmetic (I wouldn't know, because it is a
paywalled standard).
How do we want to deal with this? Do we want to implement this
(it's an obvious speed advantage)? Should it be the default?
Do we want to include this in -fcx-fortran-rules?
Best regards
Thomas
