To: J3                                                     J3/19-145r1
From: Lorri Menard
Subject: Degree trigonometric functions
Date: 2019-February-14
Reference:  m215/18-139r1, m217/18-272r1

1 Introduction

Addition of the degree trigonometric functions was approved for further
work at m217.  This paper attempts to craft specifications.

2 Specifications

These elemental intrinsics are generic and not specific.
All would be similar to their radian counterparts except that the
argument(s) or return values would be in degrees.

3 Syntax

    ACOSD (X)
    Description: Arccosine (inverse cosine) function in degrees.
    Class: Elemental function.
    Argument: X shall be of type real with a value that satisfies the
              inequality |X| <= 1, or of type complex.
    Result Characteristics:  Same as X.
    Result Value: The result has a value equal to a processor-dependent
    approximation to arccos(X). If it is real it is expressed in degrees
    and lies in the range -90 to 90.  If it is complex the real part is
    expressed in degrees and lies in the range -90 to 90.

    ASIND (X)
    Description: Arcsine (inverse sine) function in degrees.
    Class: Elemental function.
    Argument: X shall be of type real with a value that satisfies the
              inequality |X| <= 1, or of type complex.
    Result Characteristics:  Same as X.
    Result Value: The result has a value equal to a processor-dependent
    approximation to arcsin(X). If it is real it is expressed in degrees
    and lies in the range -90 to 90.  If it is complex the real part is
    expressed in degrees and lies in the range -90 to 90.


    ATAND (X) or ATAND (Y,X)
    Description: Arctangent (inverse tangent) function in degrees.
    Class: Elemental function.
    Arguments:
     Y     shall be of type real.
     X     If Y appears, X shall be of type real with the same kind type
           parameter as Y. If Y has the value zero, X shall not have the
           value zero. If Y does not appear, X shall be of type real.
    Result Characteristics:  Same as X
    Result Value: If Y appears, the result is the same as the result of
    ATAN2D (Y,X). If Y does not appear, the result has a value equal to a
    processor-dependent approximation to arctan(X).

    ATAN2D (Y,X)
    Description: Arctangent (inverse tangent) function in degrees
    Class: Elemental function.
    Arguments:
     Y     shall be of type real.
     X     X shall be of the same type and kind type
           parameter as Y. If Y has the value zero, X shall not have the
           value zero.
    Result Characteristics:  Same as X
    Result Value: The result has a value equal to a processor-dependent
    approximation to arctan(Y/X) if X != 0. If Y > zero, the result is
    positive. If Y < zero, the result is negative.  If Y = zero, the
    result is zero (if X > zero) or 180 degrees (if X < zero).
    If X = zero, the absolute value of the result is 90.

    COSD (X)
    Description: Cosine function in degrees.
    Class: Elemental function.
    Argument: X shall be of type real or complex.
    Result Characteristics:  Same as X.
    Result Value: The result has a value equal to a processor-dependent
    approximation to cos(X). If X is of type real, it is regarded as a
    value in degrees. If X is of type complex, its real part is regarded
    as a value in degrees.

    SIND (X)
    Description: Sine function in degrees.
    Class: Elemental function.
    Argument: X shall be of type real or complex.
    Result Characteristics:  Same as X.
    Result Value: The result has a value equal to a processor-dependent
    approximation to sin(X). If X is of type real, it is regarded as a
    value in degrees. If X is of type complex, its real part is regarded
    as a value in degrees.

    TAND (X)
    Description: Tangent function in degrees.
    Class: Elemental function.
    Argument: X shall be of type real or complex.
    Result Characteristics:  Same as X.
    Result Value: The result has a value equal to a processor-dependent
    approximation to tan(X). If X is of type real, it is regarded as a
    value in degrees. If X is of type complex, its real part is regarded
    as a value in degrees.

4 Edits
   To be supplied later