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SUBROUTINE CRSHFT( M, N, OFFSET, A, LDA )
*
* -- PBLAS auxiliary routine (version 2.0) --
* University of Tennessee, Knoxville, Oak Ridge National Laboratory,
* and University of California, Berkeley.
* April 1, 1998
*
* .. Scalar Arguments ..
INTEGER LDA, M, N, OFFSET
* ..
* .. Array Arguments ..
COMPLEX A( LDA, * )
* ..
*
* Purpose
* =======
*
* CRSHFT shifts rows of an m by n array A by OFFSET.
*
* Arguments
* =========
*
* M (local input) INTEGER
* On entry, M specifies the number of rows of A to be shifted.
* M must be at least zero.
*
* N (local input) INTEGER
* On entry, N specifies the number of columns of A. N must be
* at least zero.
*
* OFFSET (local input) INTEGER
* On entry, OFFSET specifies the offset by which the rows of
* A should be shifted. OFFSET can be positive or negative (see
* below for further details). When OFFSET is positive, the rows
* are shifted to the bottom. When OFFSET is negative, the rows
* of A are shifted to the top.
*
* A (local input/local output) COMPLEX array
* On entry, A is an array of dimension ( LDA, N ). On exit, A
* contains the shifted array.
*
* LDA (local input) INTEGER
* On entry, LDA specifies the leading dimension of the array A.
* LDA must be at least max( 1, M+ABS(OFFSET) ).
*
* Further Details
* ===============
*
* N N N N
* --- --- --- ---
* | 1 | | 1 | | 1 | | 7 |
* | 2 | M = 3 | 2 | | 2 | M = 3 | 8 |
* | 3 | | 3 | | 3 | | 9 |
* | 4 | | 4 | | 4 | | 4 |
* | 5 | becomes | 5 | | 5 | becomes | 5 |
* | 6 | | 6 | | 6 | | 6 |
* | 7 | | 1 | | 7 | | 7 |
* | 8 | OFFSET = 6 | 2 | | 8 | OFFSET = -6 | 8 |
* | 9 | | 3 | | 9 | | 9 |
* --- --- --- ---
* OFFSET >= 0 OFFSET <= 0
*
* -- Written on April 1, 1998 by
* Antoine Petitet, University of Tennessee, Knoxville 37996, USA.
*
* =====================================================================
*
* .. Local Scalars ..
INTEGER I, J
* ..
* .. Executable Statements ..
*
IF( ( OFFSET.EQ.0 ).OR.( M.LE.0 ).OR.( N.LE.0 ) )
$ RETURN
*
IF( OFFSET.GT.0 ) THEN
DO 20 J = 1, N
DO 10 I = M, 1, -1
A( I+OFFSET, J ) = A( I, J )
10 CONTINUE
20 CONTINUE
ELSE
DO 40 J = 1, N
DO 30 I = 1, M
A( I, J ) = A( I-OFFSET, J )
30 CONTINUE
40 CONTINUE
END IF
*
RETURN
*
* End of CRSHFT
*
END
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