Developer Reference for Intel® oneAPI Math Kernel Library for Fortran
v?ExpInt1
vsExpInt1 vdExpInt1 vmsExpInt1 vmdExpInt1 Computes the exponential integral of vector elements.
Syntax
call vsexpint1 ( n , a , y )
call vsexpint1i(n, a, inca, y, incy)
call vmsexpint1 ( n , a , y , mode )
call vmsexpint1i(n, a, inca, y, incy, mode)
call vdexpint1 ( n , a , y )
call vdexpint1i(n, a, inca, y, incy)
call vdexpint1 ( n , a , y , mode )
call vmdexpint1i(n, a, inca, y, incy, mode)
Include Files
mkl_vml.f90
Input Parameters
Name |
Type |
Description |
|---|---|---|
n |
Specifies the number of elements to be calculated. |
|
a |
Fortran 90: REAL (KIND=4) , INTENT(IN) for vsexpint1 , vmsexpint1Fortran 90: REAL (KIND=8) , INTENT(IN) for vdexpint1 , vmdexpint1 |
Array that specifies the input vector a . |
inca, incy |
INTEGER, INTENT(IN) |
Specifies increments for the elements of a and y . |
mode |
Overrides global VM mode setting for this function call. See vmlSetMode (Sets a new mode for VM functions according to the mode parameter and stores the previous VM mode to oldmode.) for possible values and their description. |
Output Parameters
Name |
Type |
Description |
|---|---|---|
y |
Array that specifies 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 |