X02 Chapter Contents
X02 Chapter Introduction
NAG Library Manual

# NAG Library Routine DocumentX02AJF

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

X02AJF returns $\epsilon$, the value machine precision.

## 2  Specification

 FUNCTION X02AJF ( )
 REAL (KIND=nag_wp) X02AJF

## 3  Description

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 (1997).

## 4  References

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

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## 9  Example

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

### 9.1  Program Text

Program Text (x02ajfe.f90)

None.

### 9.3  Program Results

Program Results (x02ajfe.r)