ATAN — Arctangent function

Description

ATAN(X) computes the arctangent of X.

Syntax

RESULT = ATAN(X)
RESULT = ATAN(Y, X)

Arguments

X The type shall be REAL or COMPLEX; if Y is present, X shall be REAL.
Y shall be of the same type and kind as X.

Return value

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.

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

Standard

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

Class

Elemental function

`X`	The type shall be `REAL` or `COMPLEX`; if `Y` is present, `X` shall be REAL.
`Y` shall be of the same type and kind as `X`.

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