1      SUBROUTINE ZCSHFT( M, N, OFFSET, A, LDA )
2*
3*  -- PBLAS auxiliary routine (version 2.0) --
4*     University of Tennessee, Knoxville, Oak Ridge National Laboratory,
5*     and University of California, Berkeley.
6*     April 1, 1998
7*
8*     .. Scalar Arguments ..
9      INTEGER            LDA, M, N, OFFSET
10*     ..
11*     .. Array Arguments ..
12      COMPLEX*16         A( LDA, * )
13*     ..
14*
15*  Purpose
16*  =======
17*
18*  ZCSHFT shifts columns of an m by n array A by OFFSET.
19*
20*  Arguments
21*  =========
22*
23*  M       (local input) INTEGER
24*          On entry,  M  specifies the number of rows of A. M must be at
25*          least zero.
26*
27*  N       (local input) INTEGER
28*          On entry,  N  specifies  the  number of columns of  A  to  be
29*          shifted. N must be at least zero.
30*
31*  OFFSET  (local input) INTEGER
32*          On entry, OFFSET specifies the offset by which the columns of
33*          A should be shifted. OFFSET  can be positive or negative (see
34*          below for further details). When OFFSET  is positive, the co-
35*          lumns are shifted to the right. When OFFSET  is negative, the
36*          columns of A are shifted to the left.
37*
38*  A       (local input/local output) COMPLEX*16 array
39*          On entry, A  is an array of dimension ( LDA, N+ABS(OFFSET) ).
40*          On exit, A contains the shifted array.
41*
42*  LDA     (local input) INTEGER
43*          On entry, LDA specifies the leading dimension of the array A.
44*          LDA must be at least max( 1, M ).
45*
46*  Further Details
47*  ===============
48*
49*             N=3     OFFSET=6                      -OFFSET=6     N=3
50*           -------------------                     -------------------
51*          | 1 2 3 4 5 6 7 8 9 |         M         | 1 2 3 4 5 6 7 8 9 |
52*           -------------------                     -------------------
53*                    V                                       V
54*           -------------------                     -------------------
55*          | 1 2 3 4 5 6 1 2 3 |         M         | 7 8 9 4 5 6 7 8 9 |
56*           -------------------                     -------------------
57*               OFFSET >= 0                             OFFSET <= 0
58*
59*  -- Written on April 1, 1998 by
60*     Antoine Petitet, University  of  Tennessee, Knoxville 37996, USA.
61*
62*  =====================================================================
63*
64*     .. Local Scalars ..
65      INTEGER            I, J
66*     ..
67*     .. Executable Statements ..
68*
69      IF( ( OFFSET.EQ.0 ).OR.( M.LE.0 ).OR.( N.LE.0 ) )
70     $   RETURN
71*
72      IF( OFFSET.GT.0 ) THEN
73         DO 20 J = N, 1, -1
74            DO 10 I = 1, M
75               A( I, J+OFFSET ) = A( I, J )
76   10       CONTINUE
77   20    CONTINUE
78      ELSE
79         DO 40 J = 1, N
80            DO 30 I = 1, M
81               A( I, J ) = A( I, J-OFFSET )
82   30       CONTINUE
83   40    CONTINUE
84      END IF
85*
86      RETURN
87*
88*     End of ZCSHFT
89*
90      END
91