01:       SUBROUTINE CROTG(CA,CB,C,S)
02: *     .. Scalar Arguments ..
03:       COMPLEX CA,CB,S
04:       REAL C
05: *     ..
06: *
07: *  Purpose
08: *  =======
09: *
10: *  CROTG determines a complex Givens rotation.
11: *
12: *     .. Local Scalars ..
13:       COMPLEX ALPHA
14:       REAL NORM,SCALE
15: *     ..
16: *     .. Intrinsic Functions ..
17:       INTRINSIC CABS,CONJG,SQRT
18: *     ..
19:       IF (CABS(CA).NE.0.) GO TO 10
20:       C = 0.
21:       S = (1.,0.)
22:       CA = CB
23:       GO TO 20
24:    10 CONTINUE
25:       SCALE = CABS(CA) + CABS(CB)
26:       NORM = SCALE*SQRT((CABS(CA/SCALE))**2+ (CABS(CB/SCALE))**2)
27:       ALPHA = CA/CABS(CA)
28:       C = CABS(CA)/NORM
29:       S = ALPHA*CONJG(CB)/NORM
30:       CA = ALPHA*NORM
31:    20 CONTINUE
32:       RETURN
33:       END
34: