PSORM2L(l) | LAPACK routine (version 1.5) | PSORM2L(l) |
NAME¶
PSORM2L - overwrite the general real M-by-N distributed matrix sub( C ) = C(IC:IC+M-1,JC:JC+N-1) with SIDE = 'L' SIDE = 'R' TRANS = 'N'SYNOPSIS¶
- SUBROUTINE PSORM2L(
- SIDE, TRANS, M, N, K, A, IA, JA, DESCA, TAU, C, IC, JC, DESCC, WORK, LWORK, INFO )
- CHARACTER
- SIDE, TRANS
- INTEGER
- IA, IC, INFO, JA, JC, K, LWORK, M, N
- INTEGER
- DESCA( * ), DESCC( * )
- REAL
- A( * ), C( * ), TAU( * ), WORK( * )
PURPOSE¶
PSORM2L overwrites the general real M-by-N distributed matrix sub( C ) = C(IC:IC+M-1,JC:JC+N-1) with TRANS = 'T': Q**T * sub( C ) sub( C ) * Q**TQ = H(k) . . . H(2) H(1)
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¶
- SIDE (global input) CHARACTER
- = 'L': apply Q or Q**T from the Left;
- TRANS (global input) CHARACTER
-
- M (global input) INTEGER
- The number of rows to be operated on i.e the number of rows of the distributed submatrix sub( C ). 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( C ). N >= 0.
- K (global input) INTEGER
- The number of elementary reflectors whose product defines the matrix Q. If SIDE = 'L', M >= K >= 0, if SIDE = 'R', N >= K >= 0.
- A (local input) REAL pointer into the local memory
- to an array of dimension (LLD_A,LOCc(JA+K-1)). On entry, the j-th column must contain the vector which defines the elemen- tary reflector H(j), JA <= j <= JA+K-1, as returned by PSGEQLF in the K columns of its distributed matrix argument A(IA:*,JA:JA+K-1). A(IA:*,JA:JA+K-1) is modified by the routine but restored on exit. If SIDE = 'L', LLD_A >= MAX( 1, LOCr(IA+M-1) ), if SIDE = 'R', LLD_A >= MAX( 1, LOCr(IA+N-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.
- TAU (local input) REAL, array, dimension LOCc(JA+N-1)
- This array contains the scalar factors TAU(j) of the elementary reflectors H(j) as returned by PSGEQLF. TAU is tied to the distributed matrix A.
- C (local input/local output) REAL pointer into the
- local memory to an array of dimension (LLD_C,LOCc(JC+N-1)). On entry, the local pieces of the distributed matrix sub(C). On exit, sub( C ) is overwritten by Q*sub( C ) or Q'*sub( C ) or sub( C )*Q' or sub( C )*Q.
- IC (global input) INTEGER
- The row index in the global array C indicating the first row of sub( C ).
- JC (global input) INTEGER
- The column index in the global array C indicating the first column of sub( C ).
- DESCC (global and local input) INTEGER array of dimension DLEN_.
- The array descriptor for the distributed matrix C.
- WORK (local workspace/local output) REAL array,
- dimension (LWORK) On exit, WORK(1) returns the minimal and optimal LWORK.
- LWORK (local or global input) INTEGER
- The dimension of the array WORK. LWORK is local input and
must be at least If SIDE = 'L', LWORK >= MpC0 + MAX( 1, NqC0 ); if SIDE
= 'R', LWORK >= NqC0 + MAX( MAX( 1, MpC0 ), NUMROC( NUMROC(
N+ICOFFC,NB_A,0,0,NPCOL ),NB_A,0,0,LCMQ ) );
- INFO (local output) INTEGER
- = 0: successful exit
12 May 1997 | LAPACK version 1.5 |