PCTRTRS(l) | LAPACK auxiliary routine (version 1.5) | PCTRTRS(l) |
NAME¶
PCTRTRS - solve a triangular system of the form sub( A ) * X = sub( B ) or sub( A )**T * X = sub( B ) or sub( A )**H * X = sub( B ),SYNOPSIS¶
- SUBROUTINE PCTRTRS(
- UPLO, TRANS, DIAG, N, NRHS, A, IA, JA, DESCA, B, IB, JB, DESCB, INFO )
- CHARACTER
- DIAG, TRANS, UPLO
- INTEGER
- IA, IB, INFO, JA, JB, N, NRHS
- INTEGER
- DESCA( * ), DESCB( * )
- COMPLEX
- A( * ), B( * )
PURPOSE¶
PCTRTRS solves a triangular system of the formDTYPE_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¶
- UPLO (global input) CHARACTER
- = 'U': sub( A ) is upper triangular;
- TRANS (global input) CHARACTER
-
- DIAG (global input) CHARACTER
-
- N (global input) INTEGER
- The number of rows and columns to be operated on i.e the order of the distributed submatrix sub( A ). N >= 0.
- NRHS (global input) INTEGER
- The number of right hand sides, i.e., the number of columns of the distributed matrix sub( B ). NRHS >= 0.
- A (local input) COMPLEX 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 triangular matrix sub( A ). If UPLO = 'U', the leading N-by-N upper triangular part of sub( A ) contains the upper triangular matrix, and the strictly lower triangular part of sub( A ) is not referenced. If UPLO = 'L', the leading N-by-N lower triangular part of sub( A ) contains the lower triangular matrix, and the strictly upper triangular part of sub( A ) is not referenced. If DIAG = 'U', the diagonal elements of sub( A ) are also not referenced and are assumed to be 1.
- 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.
- B (local input/local output) COMPLEX pointer into the
- local memory to an array of dimension (LLD_B,LOCc(JB+NRHS-1)). On entry, this array contains the local pieces of the right hand side distributed matrix sub( B ). On exit, if INFO = 0, sub( B ) is overwritten by the solution matrix X.
- IB (global input) INTEGER
- The row index in the global array B indicating the first row of sub( B ).
- JB (global input) INTEGER
- The column index in the global array B indicating the first column of sub( B ).
- DESCB (global and local input) INTEGER array of dimension DLEN_.
- The array descriptor for the distributed matrix B.
- INFO (output) INTEGER
- = 0: successful exit
12 May 1997 | LAPACK version 1.5 |