X06 Chapter Contents
X06 Chapter Introduction
NAG Library Manual

# NAG Library Routine DocumentX06AFF

Note:  before using this routine, please read the Users' Note for your implementation to check the interpretation of bold italicised terms and other implementation-dependent details.

## 1  Purpose

X06AFF returns $1$ if called from within an active OpenMP parallel region, and $0$ otherwise.

## 2  Specification

 FUNCTION X06AFF ( )
 INTEGER X06AFF

## 3  Description

X06AFF, for multi-threaded implementations, returns $1$ if called from within an active OpenMP parallel region, and $0$ otherwise.
Note that the equivalent OpenMP routine omp_in_parallel() returns a logical value.
In serial implementations of the NAG Library this routine will always return $0$. See the X06 Chapter Introduction for a discussion of the behaviour of these routines when called in serial.

## 4  References

OpenMP Specifications http://openmp.org/wp/OpenMP-Specifications
Chapman B, Jost G and van der Pas R (2008) Using OpenMP Portable Shared Memory Parallel Programming The MIT Press

None.

None.

Not applicable.

## 8  Parallelism and Performance

X06AFF is not threaded in any implementation.