Intel® Math Kernel Library 2019 Developer Reference - Fortran
Computes the base 2 logarithm of vector elements.
call vslog2 (n, a, y)
call vmslog2 (n, a, y, mode)
call vdlog2 (n, a, y)
call vmdlog2 (n, a, y, mode)
Name |
Type |
Description |
|---|---|---|
n |
INTEGER |
Specifies the number of elements to be calculated. |
a |
REAL for vslog2 REAL for vmslog2 DOUBLE PRECISION for vdlog2 DOUBLE PRECISION for vmdlog2 |
Pointer to the array containing the input vector a. |
mode |
INTEGER (KIND=8) |
Overrides the global VM mode setting for this function call. See vmlSetMode for possible values and their description. |
Name |
Type |
Description |
|---|---|---|
y |
REAL for vslog2 REAL for vmslog2 DOUBLE PRECISION for vdlog2 DOUBLE PRECISION for vmdlog2 |
Pointer to an array containing the output vector y. |
The v?Log2 function computes the base 2 logarithm of vector elements.
See Special Value Notations for the conventions used in this table:
| Argument | Result | VM Error Status | Exception |
|---|---|---|---|
| +1 | +0 | ||
| x < +0 | QNAN | VML_STATUS_ERRDOM | INVALID |
| +0 | -∞ | VML_STATUS_SING | ZERODIVIDE |
| -0 | -∞ | VML_STATUS_SING | ZERODIVIDE |
| -∞ | QNAN | VML_STATUS_ERRDOM | INVALID |
| +∞ | +∞ | ||
| QNAN | QNAN | ||
| SNAN | QNAN | INVALID |