SUBROUTINE SLASWP( N, A, LDA, K1, K2, IPIV, INCX )
*
* -- LAPACK auxiliary routine (version 3.1) --
* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
* November 2006
*
* .. Scalar Arguments ..
INTEGER INCX, K1, K2, LDA, N
* ..
* .. Array Arguments ..
INTEGER IPIV( * )
REAL A( LDA, * )
* ..
*
* 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.
*
* Arguments
* =========
*
* N (input) INTEGER
* The number of columns of the matrix A.
*
* A (input/output) 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.
*
* LDA (input) INTEGER
* The leading dimension of the array A.
*
* K1 (input) INTEGER
* The first element of IPIV for which a row interchange will
* be done.
*
* K2 (input) INTEGER
* The last element of IPIV for which a row interchange will
* be done.
*
* IPIV (input) INTEGER array, dimension (K2*abs(INCX))
* The vector of pivot indices. Only the elements in positions
* K1 through K2 of IPIV are accessed.
* IPIV(K) = L implies rows K and L are to be interchanged.
*
* INCX (input) INTEGER
* The increment between successive values of IPIV. If IPIV
* is negative, the pivots are applied in reverse order.
*
* Further Details
* ===============
*
* Modified by
* R. C. Whaley, Computer Science Dept., Univ. of Tenn., Knoxville, USA
*
* =====================================================================
*
* .. Local Scalars ..
INTEGER I, I1, I2, INC, IP, IX, IX0, J, K, N32
REAL TEMP
* ..
* .. Executable Statements ..
*
* Interchange row I with row IPIV(I) 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 = 1 + ( 1-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
*
END