Developer Reference for Intel® oneAPI Math Kernel Library for C
v?Logb
Computes the exponents of the elements of input vector a.
Syntax
vhLogb (n, a, y);
vhLogbI(n, a, inca, y, incy);
vmhLogb (n, a, y, mode);
vmhLogbI(n, a, inca, y, incy, mode);
vsLogb (n, a, y);
vsLogbI(n, a, inca, y, incy);
vmsLogb (n, a, y, mode);
vmsLogbI(n, a, inca, y, incy, mode);
vdLogb (n, a, y);
vdLogbI(n, a, inca, y, incy);
vmdLogb (n, a, y, mode);
vmdLogbI(n, a, inca, y, incy, mode);
Include Files
- mkl.h
 
Input Parameters
Name  |  
      Type  |  
      Description  |  
     
|---|---|---|
n  |  
      const MKL_INT  |  
      Specifies the number of elements to be calculated.  |  
     
a  |  
      const _Float16* for vhLogb const float* for vsLogb const _Float16* for vmhLogb const float* for vmsLogb const double* for vdLogb const double* for vmdLogb  |  
      Pointer to the array containing the input vector a.  |  
     
inca, incy  |  
      const MKL_INT  |  
      Specifies increments for the elements of a and y.  |  
     
mode  |  
      const MKL_INT64  |  
      Overrides the global VM mode setting for this function call. See vmlSetMode for possible values and their description.  |  
     
Output Parameters
Name  |  
      Type  |  
      Description  |  
     
|---|---|---|
y  |  
      _Float16* for vhLogb float* for vsLogb _Float16* for vmhLogb float* for vmsLogb double* for vdLogb double* for vmdLogb  |  
      Pointer to an array containing the output vector y.  |  
     
Description
The v?Logb function computes the exponents of the elements of the input vector a. For each element ai of vector a, this is the integral part of log2|ai|. The returned value is exact and is independent of the current rounding direction mode.
See Special Value Notations for the conventions used in this table:
| Argument | Result | VM Error Status | Exception | 
|---|---|---|---|
| +0 | -∞ | VML_STATUS_ERRDOM | ZERODIVIDE | 
| -0 | -∞ | VML_STATUS_ERRDOM | ZERODIVIDE | 
| -∞ | +∞ | ||
| +∞ | +∞ | ||
| QNAN | QNAN | ||
| SNAN | QNAN | INVALID |