To: J3                                                     J3/18-139r1
From: Steve Lionel
Subject: Degree trigonometric functions
Date: 2018-February-16

Many if not most Fortran implementations support, as extensions,
degree-argument (or return value) versions of some of the trigonometric
intrinsic functions, and these 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.

During J3 discussion it was noted:
- The hyperbolic functions (COSH, SINH, etc.) do not use radians and
  therefore need no degree equivalents.
- While ATAN2 is effectively replaced by the two-argument form of
  ATAN, it was felt appropriate to include ATAN2D in support of
  existing practice.