# NAG Library Function Document

## 1Purpose

nag_omp_in_parallel (x06afc) returns $1$ if called from within an active OpenMP parallel region, and $0$ otherwise.

## 2Specification

 #include #include
 Integer nag_omp_in_parallel ()

## 3Description

nag_omp_in_parallel (x06afc), for multi-threaded implementations, returns $1$ if called from within an active OpenMP parallel region, and $0$ otherwise.
In serial implementations of the NAG C Library this function will always return $0$. See the x06 Chapter Introduction for a discussion of the behaviour of these functions when called in serial.

## 4References

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

None.

None.

Not applicable.

## 8Parallelism and Performance

nag_omp_in_parallel (x06afc) is not threaded in any implementation.