# NAG Library Routine Document

## 1Purpose

f06flf returns the absolutely largest and absolutely smallest values from a real vector.

## 2Specification

Fortran Interface
 Subroutine f06flf ( n, x, incx, xmax, xmin)
 Integer, Intent (In) :: n, incx Real (Kind=nag_wp), Intent (In) :: x(*) Real (Kind=nag_wp), Intent (Out) :: xmax, xmin
C Header Interface
#include nagmk26.h
 void f06flf_ ( const Integer *n, const double x[], const Integer *incx, double *xmax, double *xmin)

## 3Description

f06flf returns the values ${x}_{\mathrm{max}}$ and ${x}_{\mathrm{min}}$ given by
 $xmax=maxixi, xmin=minixi,$
where $x$ is an $n$-element real vector scattered with stride incx. If $n<1$, then ${x}_{\mathrm{max}}$ and ${x}_{\mathrm{min}}$ are returned as zero.

None.

## 5Arguments

1:     $\mathbf{n}$ – IntegerInput
On entry: $n$, the number of elements in $x$.
2:     $\mathbf{x}\left(*\right)$ – Real (Kind=nag_wp) arrayInput
Note: the dimension 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.
3:     $\mathbf{incx}$ – IntegerInput
On entry: the increment in the subscripts of x between successive elements of $x$.
Constraint: ${\mathbf{incx}}>0$.
4:     $\mathbf{xmax}$ – Real (Kind=nag_wp)Output
On exit: the value ${x}_{\mathrm{max}}=\underset{i}{\mathrm{max}}\phantom{\rule{0.25em}{0ex}}\left|{x}_{i}\right|$.
5:     $\mathbf{xmin}$ – Real (Kind=nag_wp)Output
On exit: the value ${x}_{\mathrm{min}}=\underset{i}{\mathrm{min}}\phantom{\rule{0.25em}{0ex}}\left|{x}_{i}\right|$.

None.

Not applicable.

## 8Parallelism and Performance

f06flf is not threaded in any implementation.

None.

## 10Example

None.
© The Numerical Algorithms Group Ltd, Oxford, UK. 2017