34 lines
683 B
FortranFixed
34 lines
683 B
FortranFixed
SUBROUTINE CROTG(CA,CB,C,S)
|
|
* .. Scalar Arguments ..
|
|
COMPLEX CA,CB,S
|
|
REAL C
|
|
* ..
|
|
*
|
|
* Purpose
|
|
* =======
|
|
*
|
|
* CROTG determines a complex Givens rotation.
|
|
*
|
|
* .. Local Scalars ..
|
|
COMPLEX ALPHA
|
|
REAL NORM,SCALE
|
|
* ..
|
|
* .. Intrinsic Functions ..
|
|
INTRINSIC CABS,CONJG,SQRT
|
|
* ..
|
|
IF (CABS(CA).NE.0.) GO TO 10
|
|
C = 0.
|
|
S = (1.,0.)
|
|
CA = CB
|
|
GO TO 20
|
|
10 CONTINUE
|
|
SCALE = CABS(CA) + CABS(CB)
|
|
NORM = SCALE*SQRT((CABS(CA/SCALE))**2+ (CABS(CB/SCALE))**2)
|
|
ALPHA = CA/CABS(CA)
|
|
C = CABS(CA)/NORM
|
|
S = ALPHA*CONJG(CB)/NORM
|
|
CA = ALPHA*NORM
|
|
20 CONTINUE
|
|
RETURN
|
|
END
|