slaswp()

subroutine slaswp	(	integer	n,
		real, dimension( lda, * )	a,
		integer	lda,
		integer	k1,
		integer	k2,
		integer, dimension( * )	ipiv,
		integer	incx
	)

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

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Purpose:

 SLASWP 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 REAL 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 114 of file slaswp.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( * )
      REAL               A( LDA, * )
*     ..
*
* =====================================================================
*
*     .. Local Scalars ..
      INTEGER            I, I1, I2, INC, IP, IX, IX0, J, K, N32
      REAL               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 SLASWP
*

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