NAG Library Manual, Mark 30.1
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F06 (Blas) Chapter Introduction
f06cc:  FL   CL   CPP   AD   PY   MB 

NAG FL Interface
f06ccf (zcsg)

NAG Library Manual, Mark 30.1
Interfaces:  FL   CL   CPP   AD   PY   MB 
NAG FL Interface Introduction
F06 (Blas) Chapter Contents
F06 (Blas) Chapter Introduction
f06cc:  FL   CL   CPP   AD   PY   MB 

▸▿ Contents

© The Numerical Algorithms Group Ltd. 2024
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1 Purpose

f06ccf reconstructs the parameters c (real) and s (complex) of a complex plane rotation from the tangent of that rotation.

2 Specification

Fortran Interface
Subroutine f06ccf ( t, c, s)
Real (Kind=nag_wp), Intent (Out) :: c
Complex (Kind=nag_wp), Intent (In) :: t
Complex (Kind=nag_wp), Intent (Out) :: s
C Header Interface
#include <nag.h>
void  f06ccf_ (const Complex *t, double *c, Complex *s)
The routine may be called by the names f06ccf or nagf_blas_zcsg.

3 Description

f06ccf reconstructs the parameters c (real) and s (complex) of a complex plane rotation, from the value of the tangent t, as returned by f06caf:
c=11+|t|2 ,  s=ct,  
so that c is always real and non-negative.
If |t|<ε, where ε is the machine precision, the routine sets c=1 and s=t.

4 References

None.

5 Arguments

1: t – Complex (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 – Complex (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

Background information to multithreading can be found in the Multithreading documentation.
f06ccf is not threaded in any implementation.

9 Further Comments

None.

10 Example

None.
NAG Library Manual, Mark 30.1
Interfaces:  FL   CL   CPP   AD   PY   MB 
NAG FL Interface Introduction
F06 (Blas) Chapter Contents
F06 (Blas) Chapter Introduction
f06cc:  FL   CL   CPP   AD   PY   MB 
© The Numerical Algorithms Group Ltd. 2024