dlar2v()

subroutine dlar2v	(	integer	n,
		double precision, dimension( * )	x,
		double precision, dimension( * )	y,
		double precision, dimension( * )	z,
		integer	incx,
		double precision, dimension( * )	c,
		double precision, dimension( * )	s,
		integer	incc )

DLAR2V applies a vector of plane rotations with real cosines and real sines from both sides to a sequence of 2-by-2 symmetric/Hermitian matrices.

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Purpose:

!>
!> DLAR2V applies a vector of real plane rotations from both sides to
!> a sequence of 2-by-2 real symmetric matrices, defined by the elements
!> of the vectors x, y and z. For i = 1,2,...,n
!>
!>    ( x(i)  z(i) ) := (  c(i)  s(i) ) ( x(i)  z(i) ) ( c(i) -s(i) )
!>    ( z(i)  y(i) )    ( -s(i)  c(i) ) ( z(i)  y(i) ) ( s(i)  c(i) )
!> 

Parameters

[in]	N	!> N is INTEGER !> The number of plane rotations to be applied. !>
[in,out]	X	!> X is DOUBLE PRECISION array, !> dimension (1+(N-1)*INCX) !> The vector x. !>
[in,out]	Y	!> Y is DOUBLE PRECISION array, !> dimension (1+(N-1)*INCX) !> The vector y. !>
[in,out]	Z	!> Z is DOUBLE PRECISION array, !> dimension (1+(N-1)*INCX) !> The vector z. !>
[in]	INCX	!> INCX is INTEGER !> The increment between elements of X, Y and Z. INCX > 0. !>
[in]	C	!> C is DOUBLE PRECISION array, dimension (1+(N-1)*INCC) !> The cosines of the plane rotations. !>
[in]	S	!> S is DOUBLE PRECISION array, dimension (1+(N-1)*INCC) !> The sines of the plane rotations. !>
[in]	INCC	!> INCC is INTEGER !> The increment between elements of C and S. INCC > 0. !>

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 107 of file dlar2v.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            INCC, INCX, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   C( * ), S( * ), X( * ), Y( * ), Z( * )
*     ..
*
*  =====================================================================
*
*     .. Local Scalars ..
      INTEGER            I, IC, IX
      DOUBLE PRECISION   CI, SI, T1, T2, T3, T4, T5, T6, XI, YI, ZI
*     ..
*     .. Executable Statements ..
*
      ix = 1
      ic = 1
      DO 10 i = 1, n
         xi = x( ix )
         yi = y( ix )
         zi = z( ix )
         ci = c( ic )
         si = s( ic )
         t1 = si*zi
         t2 = ci*zi
         t3 = t2 - si*xi
         t4 = t2 + si*yi
         t5 = ci*xi + t1
         t6 = ci*yi - t1
         x( ix ) = ci*t5 + si*t4
         y( ix ) = ci*t6 - si*t3
         z( ix ) = ci*t4 - si*t5
         ix = ix + incx
         ic = ic + incc
   10 CONTINUE
*
*     End of DLAR2V
*
      RETURN

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