zdrot()

subroutine zdrot	(	integer	n,
		complex*16, dimension( * )	zx,
		integer	incx,
		complex*16, dimension( * )	zy,
		integer	incy,
		double precision	c,
		double precision	s
	)

ZDROT

Purpose:

 Applies a plane rotation, where the cos and sin (c and s) are real
 and the vectors cx and cy are complex.
 jack dongarra, linpack, 3/11/78.

Parameters

[in]	N	N is INTEGER On entry, N specifies the order of the vectors cx and cy. N must be at least zero.
[in,out]	ZX	ZX is COMPLEX*16 array, dimension at least ( 1 + ( N - 1 )*abs( INCX ) ). Before entry, the incremented array ZX must contain the n element vector cx. On exit, ZX is overwritten by the updated vector cx.
[in]	INCX	INCX is INTEGER On entry, INCX specifies the increment for the elements of ZX. INCX must not be zero.
[in,out]	ZY	ZY is COMPLEX*16 array, dimension at least ( 1 + ( N - 1 )*abs( INCY ) ). Before entry, the incremented array ZY must contain the n element vector cy. On exit, ZY is overwritten by the updated vector cy.
[in]	INCY	INCY is INTEGER On entry, INCY specifies the increment for the elements of ZY. INCY must not be zero.
[in]	C	C is DOUBLE PRECISION On entry, C specifies the cosine, cos.
[in]	S	S is DOUBLE PRECISION On entry, S specifies the sine, sin.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 97 of file zdrot.f.

*
*  -- Reference BLAS level1 routine --
*  -- Reference BLAS is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*
*     .. Scalar Arguments ..
      INTEGER            INCX, INCY, N
      DOUBLE PRECISION   C, S
*     ..
*     .. Array Arguments ..
      COMPLEX*16         ZX( * ), ZY( * )
*     ..
*
* =====================================================================
*
*     .. Local Scalars ..
      INTEGER            I, IX, IY
      COMPLEX*16         CTEMP
*     ..
*     .. Executable Statements ..
*
      IF( n.LE.0 )
     $   RETURN
      IF( incx.EQ.1 .AND. incy.EQ.1 ) THEN
*
*        code for both increments equal to 1
*
         DO i = 1, n
            ctemp = c*zx( i ) + s*zy( i )
            zy( i ) = c*zy( i ) - s*zx( i )
            zx( i ) = ctemp
         END DO
      ELSE
*
*        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 i = 1, n
            ctemp = c*zx( ix ) + s*zy( iy )
            zy( iy ) = c*zy( iy ) - s*zx( ix )
            zx( ix ) = ctemp
            ix = ix + incx
            iy = iy + incy
         END DO
      END IF
      RETURN
*
*     End of ZDROT
*

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