Purpose
Natural logarithm.
Class
Elemental function
Argument type and attributes
- X
- must be of type real or complex.
- If X is real, its value must be greater than zero.
- If X is complex, its value must not be zero.
Result type and attributes
Same as X.
Result value
- It has a value approximating logeX.
- For complex arguments, LOG ((a,b)) approximates LOG (ABS((a,b))) + ATAN2((b,a)).
The -qxlf2003=signdzerointr option controls whether you get Fortran 2003 behavior. See qxlf2003 in the XL Fortran Compiler Reference
-
If the argument type is complex, the result is the principal value of the imaginary part OMEGA in the range -PI < OMEGA ≤ PI. If the real part of the argument is less than zero and its imaginary part is zero, the imaginary part of the result approximates PI.
-
If the argument type is complex, the result is the
principal value of the imaginary part OMEGA
in the range -PI < OMEGA ≤ PI. If the real part of the argument is less
than zero and its imaginary part is zero, the imaginary part of the
result approximates PI if
the imaginary part of X is positive real zero. If the imaginary part
of X is negative real zero, the imaginary part of the result approximates -PI 
Examples
LOG (10.0) has the value 2.3025851 (approximately).
| Specific Name | Argument Type | Result Type | Pass As Arg? |
|---|---|---|---|
| ALOG | default real | default real | yes |
| DLOG | double precision real | double precision real | yes |
| QLOG | REAL(16) | REAL(16) | yes 1 |
| CLOG | default complex | default complex | yes |
| CDLOG | double complex | double complex | yes 1 |
| ZLOG | double complex | double complex | yes 1 |
| CQLOG | COMPLEX(16) | COMPLEX(16) | yes 1 |
Note:
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