3 * =========== DOCUMENTATION ===========
5 * Online html documentation available at
6 * http://www.netlib.org/lapack/explore-html/
11 * SUBROUTINE ZROTG(CA,CB,C,S)
13 * .. Scalar Arguments ..
24 *> ZROTG determines a double complex Givens rotation.
30 *> \author Univ. of Tennessee
31 *> \author Univ. of California Berkeley
32 *> \author Univ. of Colorado Denver
35 *> \date November 2011
37 *> \ingroup complex16_blas_level1
39 * =====================================================================
40 SUBROUTINE ZROTG(CA,CB,C,S)
42 * -- Reference BLAS level1 routine (version 3.4.0) --
43 * -- Reference BLAS is a software package provided by Univ. of Tennessee, --
44 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
47 * .. Scalar Arguments ..
52 * =====================================================================
56 DOUBLE PRECISION NORM,SCALE
58 * .. Intrinsic Functions ..
59 INTRINSIC CDABS,DCMPLX,DCONJG,DSQRT
61 IF (CDABS(CA).EQ.0.0d0) THEN
66 SCALE = CDABS(CA) + CDABS(CB)
67 NORM = SCALE*DSQRT((CDABS(CA/DCMPLX(SCALE,0.0d0)))**2+
68 $ (CDABS(CB/DCMPLX(SCALE,0.0d0)))**2)
71 S = ALPHA*DCONJG(CB)/NORM