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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