 
      SUBROUTINE CROTG(CA,CB,C,S)
C***BEGIN PROLOGUE  CROTG
C***DATE WRITTEN   790101   (YYMMDD)
C***REVISION DATE  830518   (YYMMDD)
C***CATEGORY NO.  D1B10
C***KEYWORDS  BLAS,COMPLEX,COMPLEX GIVENS TRANSFORMATION
C***AUTHOR  (NONE)
C***PURPOSE  Construct a complex Givens transformation.
C***DESCRIPTION
C
C     Complex Givens transformation
C
C      Construct the Givens transformation
C
C             (C    S)
C       G  =  (      ),  C**2 + CABS(S)**2 =1,
C             (-S   C)
C
C      which zeros the second entry of the complex 2-vector (CA,CB)**T
C
C    The quantity CA/CABS(CA)*NORM(CA,CB) overwrites CA in storage.
C
C    INPUT:
C        CA (Complex)
C        CB (Complex)
C
C    Output:
C        CA (Complex)      CA/CABS(CA)*NORM(CA,CB)
C        C  (Real)
C        S  (Complex)
C***REFERENCES  (NONE)
C***ROUTINES CALLED  (NONE)
C***END PROLOGUE  CROTG
 
 
