Re: Angle Units For Trig Functions

On Sun, 20 Oct 2024 03:47:13 +0000, Lawrence D'Oliveiro wrote:

I see that the Fortran 2023 spec has added a bunch of parallel trig
functions that work in degrees.

No. Fortran does not contain "a bunch of parallel trig functions
that work in degrees."  It contains a bunch of elemental functions.

I find this sort of thing unnecessary. It seems conventional to add
functions for converting between degrees and radians, but a simpler way is
to simply define a conversion factor for each angle unit. One conversion
factor is simpler than two functions for each angle unit.

program foo
   real x, y
   x = 30+360*1111
   y = x * (4 * atan(1.) / 180)
   print *, sind(x), sin(y)
end program foo

% gfcx -o z a.f90 && ./z
0.500000000      0.500089288

One of these values is exact, and one of these raises FE_INEXACT.

--
steve