PDORMHR(l) | LAPACK routine (version 1.5) | PDORMHR(l) |
NAME¶
PDORMHR - 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 PDORMHR(
- SIDE, TRANS, M, N, ILO, IHI, A, IA, JA, DESCA, TAU, C, IC, JC, DESCC, WORK, LWORK, INFO )
PURPOSE¶
PDORMHR 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**TDTYPE_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¶
- 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.
- ILO (global input) INTEGER
- IHI (global input) INTEGER ILO and IHI must have the same values as in the previous call of PDGEHRD. Q is equal to the unit matrix except in the distributed submatrix Q(ia+ilo:ia+ihi-1,ia+ilo:ja+ihi-1). If SIDE = 'L', 1 <= ILO <= IHI <= max(1,M); if SIDE = 'R', 1 <= ILO <= IHI <= max(1,N); ILO and IHI are relative indexes.
- A (local input) DOUBLE PRECISION pointer into the local memory
- to an array of dimension (LLD_A,LOCc(JA+M-1)) if SIDE='L', and (LLD_A,LOCc(JA+N-1)) if SIDE = 'R'. The vectors which define the elementary reflectors, as returned by PDGEHRD.
- 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) DOUBLE PRECISION, array, dimension LOCc(JA+M-2)
- if SIDE = 'L', and LOCc(JA+N-2) if SIDE = 'R'. This array contains the scalar factors TAU(j) of the elementary reflectors H(j) as returned by PDGEHRD. TAU is tied to the distributed matrix A.
- C (local input/local output) DOUBLE PRECISION 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) DOUBLE PRECISION 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 IAA = IA + ILO; JAA = JA+ILO-1; If SIDE = 'L', MI = IHI-ILO; NI = N; ICC = IC + ILO; JCC = JC; LWORK >= MAX( (NB_A*(NB_A-1))/2, (NqC0 + MpC0)*NB_A ) + NB_A * NB_A else if SIDE = 'R', MI = M; NI = IHI-ILO; ICC = IC; JCC = JC + ILO; LWORK >= MAX( (NB_A*(NB_A-1))/2, ( NqC0 + MAX( NpA0 + NUMROC( NUMROC( NI+ICOFFC, NB_A, 0, 0, NPCOL ), NB_A, 0, 0, LCMQ ), MpC0 ) )*NB_A ) + NB_A * NB_A end if where LCMQ = LCM / NPCOL with LCM = ICLM( NPROW, NPCOL ), IROFFA = MOD( IAA-1, MB_A ), ICOFFA = MOD( JAA-1, NB_A ), IAROW = INDXG2P( IAA, MB_A, MYROW, RSRC_A, NPROW ), NpA0 = NUMROC( NI+IROFFA, MB_A, MYROW, IAROW, NPROW ), IROFFC = MOD( ICC-1, MB_C ), ICOFFC = MOD( JCC-1, NB_C ), ICROW = INDXG2P( ICC, MB_C, MYROW, RSRC_C, NPROW ), ICCOL = INDXG2P( JCC, NB_C, MYCOL, CSRC_C, NPCOL ), MpC0 = NUMROC( MI+IROFFC, MB_C, MYROW, ICROW, NPROW ), NqC0 = NUMROC( NI+ICOFFC, NB_C, MYCOL, ICCOL, NPCOL ), ILCM, INDXG2P and NUMROC are ScaLAPACK tool functions; MYROW, MYCOL, NPROW and NPCOL can be determined by calling the subroutine BLACS_GRIDINFO. If LWORK = -1, then LWORK is global input and a workspace query is assumed; the routine only calculates the minimum and optimal size for all work arrays. Each of these values is returned in the first entry of the corresponding work array, and no error message is issued by PXERBLA.
- INFO (global output) INTEGER
- = 0: successful exit
12 May 1997 | LAPACK version 1.5 |