1: SUBROUTINE ZROTG(CA,CB,C,S)
2: * .. Scalar Arguments ..
3: DOUBLE COMPLEX CA,CB,S
4: DOUBLE PRECISION C
5: * ..
6: *
7: * Purpose
8: * =======
9: *
10: * ZROTG determines a double complex Givens rotation.
11: *
12: * =====================================================================
13: *
14: * .. Local Scalars ..
15: DOUBLE COMPLEX ALPHA
16: DOUBLE PRECISION NORM,SCALE
17: * ..
18: * .. Intrinsic Functions ..
19: INTRINSIC CDABS,DCMPLX,DCONJG,DSQRT
20: * ..
21: IF (CDABS(CA).NE.0.0d0) GO TO 10
22: C = 0.0d0
23: S = (1.0d0,0.0d0)
24: CA = CB
25: GO TO 20
26: 10 CONTINUE
27: SCALE = CDABS(CA) + CDABS(CB)
28: NORM = SCALE*DSQRT((CDABS(CA/DCMPLX(SCALE,0.0d0)))**2+
29: + (CDABS(CB/DCMPLX(SCALE,0.0d0)))**2)
30: ALPHA = CA/CDABS(CA)
31: C = CDABS(CA)/NORM
32: S = ALPHA*DCONJG(CB)/NORM
33: CA = ALPHA*NORM
34: 20 CONTINUE
35: RETURN
36: END
CVSweb interface <joel.bertrand@systella.fr>