F06CDF (PDF version)
F06 Chapter Contents
F06 Chapter Introduction
NAG Library Manual

NAG Library Routine Document

F06CDF

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
    9  Example

1  Purpose

F06CDF reconstructs the parameters c (complex) and s (real) of a complex plane rotation from the tangent of that rotation.

2  Specification

SUBROUTINE F06CDF ( T, C, S)
REAL (KIND=nag_wp)  S
COMPLEX (KIND=nag_wp)  T, C

3  Description

F06CDF reconstructs the parameters c (complex) and s (real) of a complex plane rotation, from the value of the tangent t, as returned by F06CBF:
c=signRett t1+t2 ,  s=ct.
If t<ε, where ε is the machine precision, the routine sets:
c=signRettt,  s=signRett.

4  References

None.

5  Parameters

1:     T – COMPLEX (KIND=nag_wp)Input
On entry: the value t, the tangent of the rotation.
2:     C – COMPLEX (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  Further Comments

None.

9  Example

None.

F06CDF (PDF version)
F06 Chapter Contents
F06 Chapter Introduction
NAG Library Manual

© The Numerical Algorithms Group Ltd, Oxford, UK. 2012