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 |