ATAN2D — Arctangent function, degrees#

ATAN2D(Y, X)#

ATAN2D(Y, X) computes the principal value of the argument function of the complex number X + i Y in degrees. This function can be used to transform from Cartesian into polar coordinates and allows to determine the angle in the correct quadrant.

Parameters:
  • Y – The type shall be REAL.

  • X – The type and kind type parameter shall be the same as Y. If Y is zero, then X must be nonzero.

Returns:

The return value has the same type and kind type parameter as Y. It is the principal value of the complex number X + i Y. If X is nonzero, then it lies in the range -180 le atan (x) leq 180. The sign is positive if Y is positive. If Y is zero, then the return value is zero if X is strictly positive, 180 if X is negative and Y is positive zero (or the processor does not handle signed zeros), and -180 if X is negative and Y is negative zero. Finally, if X is zero, then the magnitude of the result is 90.

Standard:

GNU extension, enabled with -fdec-math.

Class:

Elemental function

Syntax:
RESULT = ATAN2D(Y, X)
Example:
program test_atan2d
  real(4) :: x = 1.e0_4, y = 0.5e0_4
  x = atan2d(y,x)
end program test_atan2d
Specific names:

Name

Argument

Return type

Standard

ATAN2D(X, Y)

REAL(4) X, Y

REAL(4)

GNU extension

DATAN2D(X, Y)

REAL(8) X, Y

REAL(8)

GNU extension

See also:

Alias: ATAND — Arctangent function, degrees Radians function: ATAN2 — Arctangent function