X02 Chapter Contents
X02 Chapter Introduction
NAG Library Manual

# NAG Library Routine DocumentX02AHF

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

X02AHF returns the largest positive argument for which the Fortran intrinsic functions SIN and COS return a result with some meaningful accuracy.

## 2  Specification

 FUNCTION X02AHF ( X)
 REAL (KIND=nag_wp) X02AHF
 REAL (KIND=nag_wp) X

## 3  Description

The trigonometric functions $\mathrm{sin}$ and $\mathrm{cos}$ supplied in some compiler run-time libraries do not return accurate results when their argument is large. Often the related accuracy of a result gets progressively worse as the argument gets larger. X02AHF gives a value beyond which the compiler run-time library returns results with no relative accuracy at all. Note that some run-time libraries do return accurate results for all arguments to $\mathrm{sin}$ and $\mathrm{cos}$.

None.

## 5  Parameters

1:     X – REAL (KIND=nag_wp)Dummy

None.

None.

None.

## 9  Example

See Section 9 in X02AJF.