ATAN — Arctangent function#

ATAN(X)#

ATAN(X) computes the arctangent of X.

Parameters:
  • X – The type shall be REAL or COMPLEX ; if Y is present, X shall be REAL.

  • Y – The type and kind type parameter shall be the same as X.

Returns:

The return value is of the same type and kind as X. If Y is present, the result is identical to ATAN2(Y,X). Otherwise, it the arcus tangent of X, where the real part of the result is in radians and lies in the range -pi/2 leq Re atan(x) leq pi/2.

Standard:

Fortran 77 and later, for a complex argument and for two arguments Fortran 2008 or later

Class:

Elemental function

Syntax:
RESULT = ATAN(X)
RESULT = ATAN(Y, X)
Example:
program test_atan
  real(8) :: x = 2.866_8
  x = atan(x)
end program test_atan
Specific names:

Name

Argument

Return type

Standard

ATAN(X)

REAL(4) X

REAL(4)

Fortran 77 and later

DATAN(X)

REAL(8) X

REAL(8)

Fortran 77 and later

See also:

Inverse function: TAN — Tangent function Degrees function: ATAND — Arctangent function, degrees