Purpose
To compute the parameters for the complex Givens rotation
( C SR+SI*I ) ( XR+XI*I ) ( ZR+ZI*I )
( ) * ( ) = ( )
( -SR+SI*I C ) ( YR+YI*I ) ( 0 )
where C, SR, SI, XR, XI, YR, YI, ZR, ZI are real numbers, I is the
imaginary unit, I = SQRT(-1), and C**2 + |SR+SI*I|**2 = 1.
Specification
SUBROUTINE SG03BR( XR, XI, YR, YI, C, SR, SI, ZR, ZI )
C .. Scalar Arguments ..
DOUBLE PRECISION C, SI, SR, XI, XR, YI, YR, ZI, ZR
Arguments
Input/Output Parameters
XR, XI, (input) DOUBLE PRECISION
YR, YI (input) DOUBLE PRECISION
The given real scalars XR, XI, YR, YI.
C, (output) DOUBLE PRECISION
SR, SI, (output) DOUBLE PRECISION
ZR, ZI (output) DOUBLE PRECISION
The computed real scalars C, SR, SI, ZR, ZI defining the
complex Givens rotation and Z = ZR+ZI*I.
Numerical Aspects
The subroutine avoids unnecessary overflow.Further Comments
In the interest of speed, this routine does not check the input for errors.Example
Program Text
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NoneProgram Results
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