PSLASCL(l) | LAPACK auxiliary routine (version 1.5) | PSLASCL(l) |
NAME¶
PSLASCL - multiplie the M-by-N real distributed matrix sub( A ) denoting A(IA:IA+M-1,JA:JA+N-1) by the real scalar CTO/CFROMSYNOPSIS¶
- SUBROUTINE PSLASCL(
- TYPE, CFROM, CTO, M, N, A, IA, JA, DESCA, INFO )
PURPOSE¶
PSLASCL multiplies the M-by-N real distributed matrix sub( A ) denoting A(IA:IA+M-1,JA:JA+N-1) by the real scalar CTO/CFROM. This is done without over/underflow as long as the final result CTO * A(I,J) / CFROM does not over/underflow. TYPE specifies that sub( A ) may be full, upper triangular, lower triangular or upper Hessenberg.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¶
- TYPE (global input) CHARACTER
- TYPE indices the storage type of the input distributed matrix. = 'G': sub(
A ) is a full matrix,
- CFROM (global input) REAL
- CTO (global input) REAL The distributed matrix sub( A ) is multiplied by CTO/CFROM. A(I,J) is computed without over/underflow if the final result CTO * A(I,J) / CFROM can be represented without over/underflow. CFROM must be nonzero.
- M (global input) INTEGER
- The number of rows to be operated on i.e the number of rows of the distributed submatrix sub( A ). M >= 0.
- N (global input) INTEGER
- The number of columns to be operated on i.e the number of columns of the distributed submatrix sub( A ). N >= 0.
- A (local input/local output) REAL pointer into the
- local memory to an array of dimension (LLD_A,LOCc(JA+N-1)). This array contains the local pieces of the distributed matrix sub( A ). On exit, this array contains the local pieces of the distributed matrix multiplied by CTO/CFROM.
- 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.
- INFO (local output) INTEGER
- = 0: successful exit
12 May 1997 | LAPACK version 1.5 |