9.21 ATAN
— Arctangent function
- Description:
-
ATAN(X)
computes the arctangent of X.
- 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) |
- 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 |
- See also:
- Inverse function: TAN