F06 Chapter Contents
F06 Chapter Introduction
NAG Library Manual

# NAG Library Routine DocumentF06BHF

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.

## 1  Purpose

F06BHF applies a real similarity rotation to a $2$ by $2$ real symmetric matrix.

## 2  Specification

 SUBROUTINE F06BHF ( X, Y, Z, C, S)
 REAL (KIND=nag_wp) X, Y, Z, C, S

## 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:
 $x y y z ← c s -s c x y y z c -s s c .$

None.

## 5  Parameters

1:     X – REAL (KIND=nag_wp)Input/Output
On entry: the value $x$, the $\left(1,1\right)$ 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 $\left(1,2\right)$ or $\left(2,1\right)$ 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 $\left(2,2\right)$ 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.

None.

Not applicable.