zlacrt()

subroutine zlacrt	(	integer	n,
		complex*16, dimension( * )	cx,
		integer	incx,
		complex*16, dimension( * )	cy,
		integer	incy,
		complex*16	c,
		complex*16	s
	)

ZLACRT performs a linear transformation of a pair of complex vectors.

Download ZLACRT + dependencies [TGZ] [ZIP] [TXT]

Purpose:

 ZLACRT performs the operation

    (  c  s )( x )  ==> ( x )
    ( -s  c )( y )      ( y )

 where c and s are complex and the vectors x and y are complex.

Parameters

[in]	N	N is INTEGER The number of elements in the vectors CX and CY.
[in,out]	CX	CX is COMPLEX*16 array, dimension (N) On input, the vector x. On output, CX is overwritten with c*x + s*y.
[in]	INCX	INCX is INTEGER The increment between successive values of CX. INCX <> 0.
[in,out]	CY	CY is COMPLEX*16 array, dimension (N) On input, the vector y. On output, CY is overwritten with -s*x + c*y.
[in]	INCY	INCY is INTEGER The increment between successive values of CY. INCY <> 0.
[in]	C	C is COMPLEX*16
[in]	S	S is COMPLEX*16 C and S define the matrix [ C S ]. [ -S C ]

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 104 of file zlacrt.f.

*
*  -- LAPACK auxiliary routine --
*  -- LAPACK 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
      COMPLEX*16         C, S
*     ..
*     .. Array Arguments ..
      COMPLEX*16         CX( * ), CY( * )
*     ..
*
* =====================================================================
*
*     .. Local Scalars ..
      INTEGER            I, IX, IY
      COMPLEX*16         CTEMP
*     ..
*     .. 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
         ctemp = c*cx( ix ) + s*cy( iy )
         cy( iy ) = c*cy( iy ) - s*cx( ix )
         cx( ix ) = ctemp
         ix = ix + incx
         iy = iy + incy
   10 CONTINUE
      RETURN
*
*     Code for both increments equal to 1
*
   20 CONTINUE
      DO 30 i = 1, n
         ctemp = c*cx( i ) + s*cy( i )
         cy( i ) = c*cy( i ) - s*cx( i )
         cx( i ) = ctemp
   30 CONTINUE
      RETURN