To: J3 J3/18-272
From: Lorri Menard
Subject: Degree trigonometric functions
Date: 2018-October-16
Reference: m215/18-139r1
I Introduction
At m215 J3 agreed to consider adding degree-argument versions of
some of the trigonometric intrinsic functions.
Many, if not most, Fortran implementations support these degree-argument
versions as extensions, and they are widely used. In the spirit of
standardizing existing practice, we should add the following generic
intrinsic functions to the standard:
- ACOSD
- ASIND
- ATAN2D
- ATAND
- COSD
- SIND
- TAND
All of these would be similar to their radian counterparts
except that the argument(s) or return values would be in degrees.
II Use cases
This provides a portable mechanism for programs that have
mathematical formulas that need the actual degrees, and don't
want the overhead of converting to/from radians.
III What I have in mind
First, the prevailing principle is that only generic functions
are to be added, even if some vendors (ahem) may have provided
specific versions.
Note that the hyperbolic functions (COSH, SINH, etc.) do not
use radians and therefore need no degree equivalents.
Finally, add the generic intrinsics listed above.