Computes the exponential integral of vector elements.
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)
Name |
Type |
Description |
|---|---|---|
n |
INTEGER, INTENT(IN) |
Specifies the number of elements to be calculated. |
a |
REAL (KIND=4), INTENT(IN) for vsexpint1, vmsexpint1 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 |
INTEGER(KIND=8), INTENT(IN) |
Overrides global VM mode setting for this function call. See vmlSetMode for possible values and their description. |
Name |
Type |
Description |
|---|---|---|
y |
REAL (KIND=4), INTENT(OUT) for vsexpint1, vmsexpint1 REAL (KIND=8), INTENT(OUT) for vdexpint1, vmdexpint1 |
Array that specifies the output vector y. |
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 |