NAG Library Manual, Mark 26
NAG AD Library Manual, Mark 26
NAG C Library Manual, Mark 26
F06 (blas) Chapter Contents
F06 (blas) Chapter Introduction
NAG Library Routine Document
f06ccf (zcsg)
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NAG Library Manual, Mark 26
NAG AD Library Manual, Mark 26
NAG C Library Manual, Mark 26
F06 (blas) Chapter Contents
F06 (blas) Chapter Introduction
▸
▿
Contents
1
Purpose
2
Specification
3
Description
4
References
5
Arguments
6
Error Indicators and Warnings
7
Accuracy
8
Parallelism and Performance
9
Further Comments
10
Example
© The Numerical Algorithms Group Ltd. 2018
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 <nagmk26.h>
void
f06ccf_ (
const Complex *
t
,
double *
c
,
Complex *
s
)
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
=
1
1
+
t
2
,
s
=
c
t
,
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.
NAG Library Manual, Mark 26
NAG AD Library Manual, Mark 26
NAG C Library Manual, Mark 26
F06 (blas) Chapter Contents
F06 (blas) Chapter Introduction
© The Numerical Algorithms Group Ltd. 2018