NAG FL Interface
f06ccf (zcsg)

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+t2 ,  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

f06ccf is not threaded in any implementation.

9 Further Comments

None.

10 Example

None.