crot()

subroutine crot	(	integer	n,
		complex, dimension( * )	cx,
		integer	incx,
		complex, dimension( * )	cy,
		integer	incy,
		real	c,
		complex	s )

CROT applies a plane rotation with real cosine and complex sine to a pair of complex vectors.

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

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.
!> 

Parameters

[in]	N	!> N is INTEGER !> The number of elements in the vectors CX and CY. !>
[in,out]	CX	!> CX is COMPLEX 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 array, dimension (N) !> On input, the vector Y. !> On output, CY is overwritten with -CONJG(S)*X + C*Y. !>
[in]	INCY	!> INCY is INTEGER !> The increment between successive values of CY. INCX <> 0. !>
[in]	C	!> C is REAL !>
[in]	S	!> S is COMPLEX !> C and S define a rotation !> [ C S ] !> [ -conjg(S) C ] !> where C*C + S*CONJG(S) = 1.0. !>

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 100 of file crot.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
      REAL               C
      COMPLEX            S
*     ..
*     .. Array Arguments ..
      COMPLEX            CX( * ), CY( * )
*     ..
*
* =====================================================================
*
*     .. 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

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