# NAG CL InterfaceX02AJC (precision)

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## 1Purpose

X02AJC returns $\epsilon$, the value machine precision.

## 2Specification

 #include
 double X02AJC
The function may be called by the names: x02ajc or nag_machine_precision.

## 3Description

X02AJC is a constant defined in the C Header file.
X02AJC returns machine precision, computed as $\epsilon =\frac{1}{2}×{b}^{1-p}$, where $b$ is the arithmetic base (see X02BHC) and $p$ is the number of significant base-$b$ digits (see X02BJC).
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)

None.

None.

Not applicable.

## 8Parallelism and Performance

X02AJC is not threaded in any implementation.