Annotation of rpl/lapack/blas/zrotg.f, revision 1.7
1.1 bertrand 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: * ..
1.7 ! bertrand 21: IF (CDABS(CA).EQ.0.0d0) THEN
! 22: C = 0.0d0
! 23: S = (1.0d0,0.0d0)
! 24: CA = CB
! 25: ELSE
! 26: SCALE = CDABS(CA) + CDABS(CB)
! 27: NORM = SCALE*DSQRT((CDABS(CA/DCMPLX(SCALE,0.0d0)))**2+
! 28: $ (CDABS(CB/DCMPLX(SCALE,0.0d0)))**2)
! 29: ALPHA = CA/CDABS(CA)
! 30: C = CDABS(CA)/NORM
! 31: S = ALPHA*DCONJG(CB)/NORM
! 32: CA = ALPHA*NORM
! 33: END IF
1.1 bertrand 34: RETURN
35: END
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