Developer Reference for Intel® oneAPI Math Kernel Library for C
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v?ExpInt1
Computes the exponential integral of vector elements.
Syntax
vsExpInt1( n, a, y );
vsExpInt1I(n, a, inca, y, incy);
vmsExpInt1( n, a, y, mode );
vmsExpInt1I(n, a, inca, y, incy, mode);
vdExpInt1( n, a, y );
vdExpInt1I(n, a, inca, y, incy);
vmdExpInt1( n, a, y, mode );
vmdExpInt1I(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 float* for vsExpInt1, vmsExpInt1 const double* for vdExpInt1, vmdExpInt1  |  
      Pointer to an array that contains the input vector a.  |  
     
inca, incy  |  
      const MKL_INT  |  
      Specifies increments for the elements of a and y.  |  
     
mode  |  
      const MKL_INT64  |  
      Overrides global VM mode setting for this function call. See vmlSetMode for possible values and their description.  |  
     
Output Parameters
Name  |  
      Type  |  
      Description  |  
     
|---|---|---|
y  |  
      float* for vsExpInt1, vmsExpInt1 double* for vdExpInt1, vmdExpInt1  |  
      Pointer to an array that contains the output vector y.  |  
     
Description
The v?ExpInt1 function computes the exponential integral E1 of vector elements.
For positive real values x, this can be written as:
.
For negative real values x, the result is defined as NAN.
| Argument | Result | VM Error Status | Exception | 
|---|---|---|---|
| x < +0 | QNAN | VML_STATUS_ERRDOM | INVALID | 
| +0 | +∞ | VML_STATUS_SING | ZERODIVIDE | 
| -0 | +∞ | VML_STATUS_SING | ZERODIVIDE | 
| +∞ | +0 | ||
| -∞ | QNAN | VML_STATUS_ERRDOM | INVALID | 
| QNAN | QNAN | ||
| SNAN | QNAN | INVALID |