NAG Library Routine Document

x02ahf  (sinarg_max)

 Contents

    1  Purpose
    7  Accuracy
    10  Example

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

Fortran Interface
Function x02ahf ( x)
Real (Kind=nag_wp):: x02ahf
Real (Kind=nag_wp), Intent (In):: x
C Header Interface
#include nagmk26.h
double  x02ahf_ ( double *x)

3
Description

The trigonometric functions sin and 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 sin and cos.

4
References

None.

5
Arguments

1:     x – Real (Kind=nag_wp)Dummy

6
Error Indicators and Warnings

None.

7
Accuracy

None.

8
Parallelism and Performance

x02ahf is not threaded in any implementation.

9
Further Comments

None.

10
Example

See Section 10 in x02ajf.
© The Numerical Algorithms Group Ltd, Oxford, UK. 2017