table of contents
PZLAQGE(l) | LAPACK auxiliary routine (version 1.5) | PZLAQGE(l) |
NAME¶
PZLAQGE - equilibrate a general M-by-N distributed matrix sub( A ) = A(IA:IA+M-1,JA:JA+N-1) using the row and scaling factors in the vectors R and CSYNOPSIS¶
- SUBROUTINE PZLAQGE(
- M, N, A, IA, JA, DESCA, R, C, ROWCND, COLCND, AMAX, EQUED )
- CHARACTER
- EQUED
- INTEGER
- IA, JA, M, N
- DOUBLE
- PRECISION AMAX, COLCND, ROWCND
- INTEGER
- DESCA( * )
- DOUBLE
- PRECISION C( * ), R( * )
- COMPLEX*16
- A( * )
PURPOSE¶
PZLAQGE equilibrates a general M-by-N distributed matrix sub( A ) = A(IA:IA+M-1,JA:JA+N-1) using the row and scaling factors in the vectors R and C.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)).
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¶
- 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) COMPLEX*16 pointer into the
- local memory to an array of dimension (LLD_A,LOCc(JA+N-1)) containing on entry the M-by-N matrix sub( A ). On exit, the equilibrated distributed matrix. See EQUED for the form of the equilibrated distributed submatrix.
- 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.
- R (local input) DOUBLE PRECISION array, dimension LOCr(M_A)
- The row scale factors for sub( A ). R is aligned with the distributed matrix A, and replicated across every process column. R is tied to the distributed matrix A.
- C (local input) DOUBLE PRECISION array, dimension LOCc(N_A)
- The column scale factors of sub( A ). C is aligned with the distributed matrix A, and replicated down every process row. C is tied to the distributed matrix A.
- ROWCND (global input) DOUBLE PRECISION
- The global ratio of the smallest R(i) to the largest R(i), IA <= i <= IA+M-1.
- COLCND (global input) DOUBLE PRECISION
- The global ratio of the smallest C(i) to the largest C(i), JA <= j <= JA+N-1.
- AMAX (global input) DOUBLE PRECISION
- Absolute value of largest distributed submatrix entry.
- EQUED (global output) CHARACTER
- Specifies the form of equilibration that was done. = 'N':
No equilibration
PARAMETERS¶
THRESH is a threshold value used to decide if row or column scaling should be done based on the ratio of the row or column scaling factors. If ROWCND < THRESH, row scaling is done, and if COLCND < THRESH, column scaling is done.12 May 1997 | LAPACK version 1.5 |