[Bug libfortran/93871] COTAN is slow for complex types

[thenlich at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93871

--- Comment #37 from Thomas Henlich <thenlich at gcc dot gnu.org> ---
It would make sense to keep optimization in mind:

Several calls to conversions of the same value should be performed only once.

As a special case: Calls to compute sind(x) and cosd(x) should be optimized to
a conversion, followed by a call to sincos.

The conversion could also be provided as a user function, for example in code
like y=tand(x)-deg2rad(x) the conversion would need to be performed only once.