1: $n$ – Integer Input: On entry: $n$ , the number of elements in $x$ .
2: $alpha$ – Real (Kind=nag_wp) Input: On entry: the scalar $α$ .

Constraint: $alpha \neq 0.0$ .
3: $x (*)$ – Real (Kind=nag_wp) array Input/Output: Note: the dimension of the array x must be at least $\max (1, 1 + (n - 1) \times incx)$ .

On entry: the $n$ -element vector $x$ . $x_{i}$ must be stored in $x (1 + (i - 1) \times incx)$ , for $i = 1, 2, \dots, n$ .
Intermediate elements of x are not referenced.

On exit: the updated vector $x$ , stored in the same array elements used to supply the original vector.
4: $incx$ – Integer Input: On entry: the increment in the subscripts of x between successive elements of $x$ .

Constraint: $incx > 0$ .

6 Error Indicators and Warnings

None.

7 Accuracy

Not applicable.

8 Parallelism and Performance

f06fef makes calls to BLAS and/or LAPACK routines, which may be threaded within the vendor library used by this implementation. Consult the documentation for the vendor library for further information.

Please consult the X06 Chapter Introduction for information on how to control and interrogate the OpenMP environment used within this routine. Please also consult the Users' Note for your implementation for any additional implementation-specific information.