ScaLAPACK 2.1  2.1
ScaLAPACK: Scalable Linear Algebra PACKage
PB_Cspan.c
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1 /* ---------------------------------------------------------------------
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 * ---------------------------------------------------------------------
9 */
10 /*
11 * Include files
12 */
13 #include "../pblas.h"
14 #include "../PBpblas.h"
15 #include "../PBtools.h"
16 #include "../PBblacs.h"
17 #include "../PBblas.h"
18 
19 #ifdef __STDC__
20 int PB_Cspan( int N, int I, int INB, int NB, int SRCPROC, int NPROCS )
21 #else
22 int PB_Cspan( N, I, INB, NB, SRCPROC, NPROCS )
23 /*
24 * .. Scalar Arguments ..
25 */
26  int I, INB, N, NB, NPROCS, SRCPROC;
27 #endif
28 {
29 /*
30 * Purpose
31 * =======
32 *
33 * PB_Cspan returns 1 if the rows (resp. columns) I:I+N-1 spans more
34 * than one process row (resp. column) and 0 otherwise.
35 *
36 * Arguments
37 * =========
38 *
39 * N (global input) INTEGER
40 * On entry, N specifies the number of rows/columns being dealt
41 * out. N must be at least zero.
42 *
43 * I (global input) INTEGER
44 * On entry, I specifies the global index of the matrix entry.
45 * I must be at least zero.
46 *
47 * INB (global input) INTEGER
48 * On entry, INB specifies the size of the first block of the
49 * global matrix distribution. INB must be at least one.
50 *
51 * NB (global input) INTEGER
52 * On entry, NB specifies the size of the blocks used to parti-
53 * tion the matrix. NB must be at least one.
54 *
55 * SRCPROC (global input) INTEGER
56 * On entry, if SRCPROC = -1, the data is not distributed but
57 * replicated, in which case this routine return 0.
58 *
59 * NPROCS (global input) INTEGER
60 * On entry, NPROCS specifies the total number of process rows
61 * or columns over which the matrix is distributed. NPROCS must
62 * be at least one.
63 *
64 * -- Written on April 1, 1998 by
65 * Antoine Petitet, University of Tennessee, Knoxville 37996, USA.
66 *
67 * ---------------------------------------------------------------------
68 */
69 /* ..
70 * .. Executable Statements ..
71 *
72 */
73 /*
74 * If the data is replicated or if there is only one process in this dimension
75 * of the process grid, the data does not span multiple processes. Finally, the
76 * case where I belongs to the first block is handled separately.
77 */
78  return( ( SRCPROC >= 0 ) &&
79  ( ( NPROCS > 1 ) &&
80  ( ( I < INB ) ? ( I + N > INB ) :
81  ( I + N > INB + ( ( I - INB ) / NB + 1 ) * NB ) ) ) );
82 /*
83 * End of PB_Cspan
84 */
85 }
PB_Cspan
int PB_Cspan(int N, int I, int INB, int NB, int SRCPROC, int NPROCS)
Definition: PB_Cspan.c:22