SCALAPACK 2.2.2
LAPACK: Linear Algebra PACKage
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◆ scshft()

subroutine scshft ( integer  m,
integer  n,
integer  offset,
real, dimension( lda, * )  a,
integer  lda 
)

Definition at line 1 of file scshft.f.

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 REAL A( LDA, * )
13* ..
14*
15* Purpose
16* =======
17*
18* SCSHFT 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) REAL 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 SCSHFT
89*