NAG FL Interface
f06bhf (drot2)

1 Purpose

f06bhf applies a real similarity rotation to a 2 by 2 real symmetric matrix.

2 Specification

Fortran Interface
Subroutine f06bhf ( x, y, z, c, s)
Real (Kind=nag_wp), Intent (In) :: c, s
Real (Kind=nag_wp), Intent (Inout) :: x, y, z
C Header Interface
#include <nag.h>
void  f06bhf_ (double *x, double *y, double *z, const double *c, const double *s)
The routine may be called by the names f06bhf or nagf_blas_drot2.

3 Description

f06bhf applies a real similarity rotation, with parameters c and s, to a given 2 by 2 real symmetric matrix; that is, it performs the operation:
x y y z c s -s c x y y z c -s s c .  

4 References

None.

5 Arguments

1: x Real (Kind=nag_wp) Input/Output
On entry: the value x, the 1,1 element of the input matrix.
On exit: the transformed value x.
2: y Real (Kind=nag_wp) Input/Output
On entry: the value y, the 1,2 or 2,1 element of the input matrix.
On exit: the transformed value y.
3: z Real (Kind=nag_wp) Input/Output
On entry: the value z, the 2,2 element of the input matrix.
On exit: the transformed value z.
4: c Real (Kind=nag_wp) Input
On entry: the value c, the cosine of the rotation.
5: s Real (Kind=nag_wp) Input
On entry: the value s, the sine of the rotation.

6 Error Indicators and Warnings

None.

7 Accuracy

Not applicable.

8 Parallelism and Performance

f06bhf is not threaded in any implementation.

9 Further Comments

None.

10 Example

None.