Purpose
To compute the parameters for the complex Givens rotation
( CR-CI*I SR-SI*I ) ( XR+XI*I ) ( Z )
( ) * ( ) = ( ),
( -SR-SI*I CR+CI*I ) ( YR+YI*I ) ( 0 )
where CR, CI, SR, SI, XR, XI, YR, YI are real numbers and I is the
imaginary unit, I = SQRT(-1). Z is a non-negative real number.
Specification
SUBROUTINE SG03BY( XR, XI, YR, YI, CR, CI, SR, SI, Z )
C .. Scalar Arguments ..
DOUBLE PRECISION CI, CR, SI, SR, XI, XR, YI, YR, Z
Arguments
Input/Output Parameters
XR, XI, (input) DOUBLE PRECISION
YR, YI (input) DOUBLE PRECISION
The given real scalars XR, XI, YR, YI.
CR, CI, (output) DOUBLE PRECISION
SR, SI, (output) DOUBLE PRECISION
Z (output) DOUBLE PRECISION
The computed real scalars CR, CI, SR, SI, Z, defining the
complex Givens rotation and Z.
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
NoneProgram Data
NoneProgram Results
None