# NAG Library Routine Document

## 1Purpose

x02ajf returns $\epsilon$, the value machine precision.

## 2Specification

Fortran Interface
 Function x02ajf ( )
 Real (Kind=nag_wp) :: x02ajf
#include nagmk26.h
 double x02ajf_ ()

## 3Description

x02ajf returns machine precision, computed as $\epsilon =\frac{1}{2}×{b}^{1-p}$, where $b$ is the arithmetic base (see x02bhf) and $p$ is the number of significant base-$b$ digits (see x02bjf).
It is important to note that the definition of $\epsilon$ here differs from that in ISO Fortran 95 (1997).

## 4References

ISO Fortran 95 (1997) ISO Fortran 95 programming language (ISO/IEC 1539–1:1997)

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## 8Parallelism and Performance

x02ajf is not threaded in any implementation.

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## 10Example

This example prints the values of all the functions in Chapter X02. The results will vary from one implementation of the Library to another.

### 10.1Program Text

Program Text (x02ajfe.f90)

None.

### 10.3Program Results

Program Results (x02ajfe.r)

© The Numerical Algorithms Group Ltd, Oxford, UK. 2017