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SUBROUTINE CROT( N, CX, INCX, CY, INCY, C, S )
*
* -- LAPACK auxiliary routine (version 3.0) --
* Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
* Courant Institute, Argonne National Lab, and Rice University
* October 31, 1992
*
* .. Scalar Arguments ..
INTEGER INCX, INCY, N
REAL C
COMPLEX S
* ..
* .. Array Arguments ..
COMPLEX CX( * ), CY( * )
* ..
*
* Purpose
* =======
*
* CROT applies a plane rotation, where the cos (C) is real and the
* sin (S) is complex, and the vectors CX and CY are complex.
*
* Arguments
* =========
*
* N (input) INTEGER
* The number of elements in the vectors CX and CY.
*
* CX (input/output) COMPLEX array, dimension (N)
* On input, the vector X.
* On output, CX is overwritten with C*X + S*Y.
*
* INCX (input) INTEGER
* The increment between successive values of CY. INCX <> 0.
*
* CY (input/output) COMPLEX array, dimension (N)
* On input, the vector Y.
* On output, CY is overwritten with -CONJG(S)*X + C*Y.
*
* INCY (input) INTEGER
* The increment between successive values of CY. INCX <> 0.
*
* C (input) REAL
* S (input) COMPLEX
* C and S define a rotation
* [ C S ]
* [ -conjg(S) C ]
* where C*C + S*CONJG(S) = 1.0.
*
* =====================================================================
*
* .. Local Scalars ..
INTEGER I, IX, IY
COMPLEX STEMP
* ..
* .. Intrinsic Functions ..
INTRINSIC CONJG
* ..
* .. Executable Statements ..
*
IF( N.LE.0 )
$ RETURN
IF( INCX.EQ.1 .AND. INCY.EQ.1 )
$ GO TO 20
*
* Code for unequal increments or equal increments not equal to 1
*
IX = 1
IY = 1
IF( INCX.LT.0 )
$ IX = ( -N+1 )*INCX + 1
IF( INCY.LT.0 )
$ IY = ( -N+1 )*INCY + 1
DO 10 I = 1, N
STEMP = C*CX( IX ) + S*CY( IY )
CY( IY ) = C*CY( IY ) - CONJG( S )*CX( IX )
CX( IX ) = STEMP
IX = IX + INCX
IY = IY + INCY
10 CONTINUE
RETURN
*
* Code for both increments equal to 1
*
20 CONTINUE
DO 30 I = 1, N
STEMP = C*CX( I ) + S*CY( I )
CY( I ) = C*CY( I ) - CONJG( S )*CX( I )
CX( I ) = STEMP
30 CONTINUE
RETURN
END
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