PSLASWP(l) | LAPACK auxiliary routine (version 1.5) | PSLASWP(l) |
NAME¶
PSLASWP - perform a series of row or column interchanges on the distributed matrix sub( A ) = A(IA:IA+M-1,JA:JA+N-1)SYNOPSIS¶
- SUBROUTINE PSLASWP(
- DIREC, ROWCOL, N, A, IA, JA, DESCA, K1, K2, IPIV )
PURPOSE¶
PSLASWP performs a series of row or column interchanges on the distributed matrix sub( A ) = A(IA:IA+M-1,JA:JA+N-1). One interchange is initiated for each of rows or columns K1 trough K2 of sub( A ). This routine assumes that the pivoting information has already been broadcast along the process row or column.DTYPE_A = 1.
the BLACS process grid A is distribu-
ted over. The context itself is glo-
bal, but the handle (the integer
value) may vary.
array A.
array A.
the rows of the array.
the columns of the array.
row of the array A is distributed. CSRC_A (global) DESCA( CSRC_ ) The process column over which the
first column of the array A is
distributed.
array. LLD_A >= MAX(1,LOCr(M_A)). Let K be the number of rows or columns of a distributed matrix, and assume that its process grid has dimension p x q.
LOCr( M ) = NUMROC( M, MB_A, MYROW, RSRC_A, NPROW ),
LOCc( N ) = NUMROC( N, NB_A, MYCOL, CSRC_A, NPCOL ). An upper bound for these quantities may be computed by:
LOCr( M ) <= ceil( ceil(M/MB_A)/NPROW )*MB_A
LOCc( N ) <= ceil( ceil(N/NB_A)/NPCOL )*NB_A
ARGUMENTS¶
- DIREC (global input) CHARACTER
- Specifies in which order the permutation is applied: = 'F' (Forward) = 'B' (Backward)
- ROWCOL (global input) CHARACTER
- Specifies if the rows or columns are permuted: = 'R' (Rows) = 'C' (Columns)
- N (global input) INTEGER
- If ROWCOL = 'R', the length of the rows of the distributed matrix A(*,JA:JA+N-1) to be permuted; If ROWCOL = 'C', the length of the columns of the distributed matrix A(IA:IA+N-1,*) to be permuted.
- A (local input/local output) REAL pointer into the
- local memory to an array of dimension (LLD_A, * ). On entry, this array contains the local pieces of the distri- buted matrix to which the row/columns interchanges will be applied. On exit the permuted distributed matrix.
- IA (global input) INTEGER
- The row index in the global array A indicating the first row of sub( A ).
- JA (global input) INTEGER
- The column index in the global array A indicating the first column of sub( A ).
- DESCA (global and local input) INTEGER array of dimension DLEN_.
- The array descriptor for the distributed matrix A.
- K1 (global input) INTEGER
- The first element of IPIV for which a row or column inter- change will be done.
- K2 (global input) INTEGER
- The last element of IPIV for which a row or column inter- change will be done.
- IPIV (local input) INTEGER array, dimension LOCr(M_A)+MB_A for
- row pivoting and LOCc(N_A)+NB_A for column pivoting. This array is tied to the matrix A, IPIV(K) = L implies rows (or columns) K and L are to be interchanged.
12 May 1997 | LAPACK version 1.5 |