nag_drscl (f06fec) (PDF version)
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NAG Library Manual

# NAG Library Function Documentnag_drscl (f06fec)

## 1  Purpose

nag_drscl (f06fec) multiplies a real vector by the reciprocal of a scalar.

## 2  Specification

 #include #include
 void nag_drscl (Integer n, double alpha, double x[], Integer incx)

## 3  Description

nag_drscl (f06fec) performs the operation
 $x←1 α x$
where $x$ is an $n$-element real vector scattered with stride incx and $\alpha$ is a real nonzero scalar.
None.

## 5  Arguments

1:     nIntegerInput
On entry: $n$, the number of elements in $x$.
2:     alphadoubleInput
On entry: the scalar $\alpha$.
Constraint: ${\mathbf{alpha}}\ne 0.0$.
3:     x[$\mathit{dim}$]doubleInput/Output
Note: the dimension, dim, of the array x must be at least $\mathrm{max}\phantom{\rule{0.125em}{0ex}}\left(1,1+\left({\mathbf{n}}-1\right)×{\mathbf{incx}}\right)$.
On entry: the $n$-element vector $x$. ${x}_{\mathit{i}}$ must be stored in ${\mathbf{x}}\left[1+\left(\mathit{i}-1\right)×{\mathbf{incx}}\right]$, for $\mathit{i}=1,2,\dots ,{\mathbf{n}}$.
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:     incxIntegerInput
On entry: the increment in the subscripts of x between successive elements of $x$.
Constraint: ${\mathbf{incx}}>0$.

None.

Not applicable.

## 8  Parallelism and Performance

nag_drscl (f06fec) is not threaded by NAG in any implementation.
nag_drscl (f06fec) 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 Users' Note for your implementation for any additional implementation-specific information.

None.

## 10  Example

None.

nag_drscl (f06fec) (PDF version)
f06 Chapter Contents
f06 Chapter Introduction
NAG Library Manual