Developer Reference for Intel® oneAPI Math Kernel Library for C

ID 766684
Date 3/31/2023
Public

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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.

Special Values for Real Function v?ExpInt1(x)
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