NAG FL Interface
f06fef (drscl)

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1 Purpose

f06fef multiplies a real vector by the reciprocal of a scalar.

2 Specification

Fortran Interface
Subroutine f06fef ( n, alpha, x, incx)
Integer, Intent (In) :: n, incx
Real (Kind=nag_wp), Intent (In) :: alpha
Real (Kind=nag_wp), Intent (Inout) :: x(*)
C Header Interface
#include <nag.h>
void  f06fef_ (const Integer *n, const double *alpha, double x[], const Integer *incx)
The routine may be called by the names f06fef or nagf_blas_drscl.

3 Description

f06fef performs the operation
x1 α x  
where x is an n-element real vector scattered with stride incx and α is a real nonzero scalar.

4 References


5 Arguments

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: alpha0.0.
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) ×incx ) .
On entry: the n-element vector x. xi must be stored in x(1+(i-1)×incx), for i=1,2,,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


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.

9 Further Comments


10 Example