Purpose
Arctangent (inverse tangent) function.
Class
Elemental function
Argument type and attributes
- X
- An INTENT(IN) REAL
or COMPLEX.
Result type and attributes
Same as X.
Result value
If X is of type real, the
result value is as follows:
- It is expressed in radians and approximates arctan(X).
- It is in the range -PI/2 ≤ ATAN(X) ≤ PI/2.
If X is of type complex, the real part of the
result value is as follows:
- It is expressed in radians.
- It is in the range -PI/2 ≤ REAL(ATAN(X)) ≤ PI/2.
Examples
ATAN(1.0) approximates PI/4.
ATAN((1.557408, 0.000000)) has the
value (1.000000, 0.000000), approximately.
| Specific Name | Argument Type | Result Type | Pass As Arg? |
|---|---|---|---|
| ATAN | default real | default real | yes |
| DATAN | double precision real | double precision real | yes |
| QATAN 1 | REAL(16) | REAL(16) | yes |
Note:
- IBM extension.