dlaswp()

subroutine dlaswp	(	integer	n,
		double precision, dimension( lda, * )	a,
		integer	lda,
		integer	k1,
		integer	k2,
		integer, dimension( * )	ipiv,
		integer	incx )

DLASWP performs a series of row interchanges on a general rectangular matrix.

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Purpose:

!>
!> DLASWP performs a series of row interchanges on the matrix A.
!> One row interchange is initiated for each of rows K1 through K2 of A.
!> 

Parameters

[in]	N	!> N is INTEGER !> The number of columns of the matrix A. !>
[in,out]	A	!> A is DOUBLE PRECISION array, dimension (LDA,N) !> On entry, the matrix of column dimension N to which the row !> interchanges will be applied. !> On exit, the permuted matrix. !>
[in]	LDA	!> LDA is INTEGER !> The leading dimension of the array A. !>
[in]	K1	!> K1 is INTEGER !> The first element of IPIV for which a row interchange will !> be done. !>
[in]	K2	!> K2 is INTEGER !> (K2-K1+1) is the number of elements of IPIV for which a row !> interchange will be done. !>
[in]	IPIV	!> IPIV is INTEGER array, dimension (K1+(K2-K1)*abs(INCX)) !> The vector of pivot indices. Only the elements in positions !> K1 through K1+(K2-K1)*abs(INCX) of IPIV are accessed. !> IPIV(K1+(K-K1)*abs(INCX)) = L implies rows K and L are to be !> interchanged. !>
[in]	INCX	!> INCX is INTEGER !> The increment between successive values of IPIV. If INCX !> is negative, the pivots are applied in reverse order. !>

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Further Details:

!>
!>  Modified by
!>   R. C. Whaley, Computer Science Dept., Univ. of Tenn., Knoxville, USA
!> 

Definition at line 112 of file dlaswp.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, K1, K2, LDA, N
*     ..
*     .. Array Arguments ..
      INTEGER            IPIV( * )
      DOUBLE PRECISION   A( LDA, * )
*     ..
*
* =====================================================================
*
*     .. Local Scalars ..
      INTEGER            I, I1, I2, INC, IP, IX, IX0, J, K, N32
      DOUBLE PRECISION   TEMP
*     ..
*     .. Executable Statements ..
*
*     Interchange row I with row IPIV(K1+(I-K1)*abs(INCX)) for each of rows
*     K1 through K2.
*
      IF( incx.GT.0 ) THEN
         ix0 = k1
         i1 = k1
         i2 = k2
         inc = 1
      ELSE IF( incx.LT.0 ) THEN
         ix0 = k1 + ( k1-k2 )*incx
         i1 = k2
         i2 = k1
         inc = -1
      ELSE
         RETURN
      END IF
*
      n32 = ( n / 32 )*32
      IF( n32.NE.0 ) THEN
         DO 30 j = 1, n32, 32
            ix = ix0
            DO 20 i = i1, i2, inc
               ip = ipiv( ix )
               IF( ip.NE.i ) THEN
                  DO 10 k = j, j + 31
                     temp = a( i, k )
                     a( i, k ) = a( ip, k )
                     a( ip, k ) = temp
   10             CONTINUE
               END IF
               ix = ix + incx
   20       CONTINUE
   30    CONTINUE
      END IF
      IF( n32.NE.n ) THEN
         n32 = n32 + 1
         ix = ix0
         DO 50 i = i1, i2, inc
            ip = ipiv( ix )
            IF( ip.NE.i ) THEN
               DO 40 k = n32, n
                  temp = a( i, k )
                  a( i, k ) = a( ip, k )
                  a( ip, k ) = temp
   40          CONTINUE
            END IF
            ix = ix + incx
   50    CONTINUE
      END IF
*
      RETURN
*
*     End of DLASWP
*

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