F06BCF (PDF version)
F06 Chapter Contents
F06 Chapter Introduction
NAG Library Manual

NAG Library Routine Document

F06BCF

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.

 Contents

    1  Purpose
    7  Accuracy
    10  Example

1  Purpose

F06BCF reconstructs the parameters c and s of a real plane rotation from the tangent of that rotation.

2  Specification

SUBROUTINE F06BCF ( T, C, S)
REAL (KIND=nag_wp)  T, C, S

3  Description

F06BCF reconstructs the parameters c and s of a real plane rotation from the value of the tangent t, as returned by F06BAF:
c=11+t2 ,  s=ct,  
so that c0 and s has the same sign as t.
If t<ε, where ε is the machine precision, the routine sets c=1 and s=t; if t>1/ε, the routine sets c= 1t  and s=signt.

4  References

None.

5  Parameters

1:     T – REAL (KIND=nag_wp)Input
On entry: the value t, the tangent of the rotation.
2:     C – REAL (KIND=nag_wp)Output
On exit: the value c, the cosine of the rotation.
3:     S – REAL (KIND=nag_wp)Output
On exit: the value s, the sine of the rotation.

6  Error Indicators and Warnings

None.

7  Accuracy

Not applicable.

8  Parallelism and Performance

Not applicable.

9  Further Comments

None.

10  Example

None.

F06BCF (PDF version)
F06 Chapter Contents
F06 Chapter Introduction
NAG Library Manual

© The Numerical Algorithms Group Ltd, Oxford, UK. 2015