SUBROUTINE PZMATADD( M, N, ALPHA, A, IA, JA, DESCA, BETA, C, IC, $ JC, DESCC ) * * -- ScaLAPACK tools routine (version 1.7) -- * University of Tennessee, Knoxville, Oak Ridge National Laboratory, * and University of California, Berkeley. * May 1, 1997 * * .. Scalar Arguments .. INTEGER IA, IC, JA, JC, M, N COMPLEX*16 ALPHA, BETA * .. * .. Array Arguments .. INTEGER DESCA( * ), DESCC( * ) COMPLEX*16 A( * ), C( * ) * .. * * Purpose * ======= * * PZMATADD performs a distributed matrix-matrix addition * * sub( C ) := alpha * sub( A ) + beta * sub( C ), * * where sub( C ) denotes C(IC:IC+M-1,JC:JC+N-1) and sub( A ) denotes * A(IA:IA+M-1,JA:JA+N-1). No communications are performed in this * routine, the arrays are supposed to be aligned. * * Notes * ===== * * Each global data object is described by an associated description * vector. This vector stores the information required to establish * the mapping between an object element and its corresponding process * and memory location. * * Let A be a generic term for any 2D block cyclicly distributed array. * Such a global array has an associated description vector DESCA. * In the following comments, the character _ should be read as * "of the global array". * * NOTATION STORED IN EXPLANATION * --------------- -------------- -------------------------------------- * DTYPE_A(global) DESCA( DTYPE_ )The descriptor type. In this case, * DTYPE_A = 1. * CTXT_A (global) DESCA( CTXT_ ) The BLACS context handle, indicating * the BLACS process grid A is distribu- * ted over. The context itself is glo- * bal, but the handle (the integer * value) may vary. * M_A (global) DESCA( M_ ) The number of rows in the global * array A. * N_A (global) DESCA( N_ ) The number of columns in the global * array A. * MB_A (global) DESCA( MB_ ) The blocking factor used to distribute * the rows of the array. * NB_A (global) DESCA( NB_ ) The blocking factor used to distribute * the columns of the array. * RSRC_A (global) DESCA( RSRC_ ) The process row over which the first * 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. * LLD_A (local) DESCA( LLD_ ) The leading dimension of the local * 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( K ) denotes the number of elements of K that a process * would receive if K were distributed over the p processes of its * process column. * Similarly, LOCc( K ) denotes the number of elements of K that a * process would receive if K were distributed over the q processes of * its process row. * The values of LOCr() and LOCc() may be determined via a call to the * ScaLAPACK tool function, NUMROC: * 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 submatrices sub( A ) and 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 submatrices sub( A ) and * sub( C ). N >= 0. * * ALPHA (global input) COMPLEX*16 * The scalar ALPHA. * * A (local input) COMPLEX*16 pointer into the local memory * to a local array of dimension (LLD_A, LOCc(JA+N-1) ). This * array contains the local pieces of the distributed matrix * sub( A ). * * 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. * * BETA (global input) COMPLEX*16 * The scalar BETA. * * C (local input/local output) COMPLEX*16 pointer into the * local memory to an array of dimension (LLD_C,LOCc(JC+N-1)). * This array contains the local pieces of the distributed * matrix sub( C ). On exit, this array contains the local * pieces of the resulting distributed matrix. * * 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. * * ===================================================================== * * .. Parameters .. INTEGER BLOCK_CYCLIC_2D, CSRC_, CTXT_, DLEN_, DTYPE_, $ LLD_, MB_, M_, NB_, N_, RSRC_ PARAMETER ( BLOCK_CYCLIC_2D = 1, DLEN_ = 9, DTYPE_ = 1, $ CTXT_ = 2, M_ = 3, N_ = 4, MB_ = 5, NB_ = 6, $ RSRC_ = 7, CSRC_ = 8, LLD_ = 9 ) COMPLEX*16 ZERO, ONE PARAMETER ( ZERO = ( 0.0D+0, 0.0D+0 ), $ ONE = ( 1.0D+0, 0.0D+0 ) ) * .. * .. Local Scalars .. INTEGER I, IACOL, IAROW, ICCOL, ICOFF, ICROW, IIA, $ IIC, IOFFA, IOFFC, IROFF, J, JJA, JJC, LDA, $ LDC, MP, MYCOL, MYROW, NPCOL, NPROW, NQ * .. * .. External Subroutines .. EXTERNAL BLACS_GRIDINFO, INFOG2L * .. * .. External Functions .. INTEGER NUMROC EXTERNAL NUMROC * .. * .. Executable Statements .. * * Get grid parameters. * CALL BLACS_GRIDINFO( DESCA(CTXT_), NPROW, NPCOL, MYROW, MYCOL ) * * Quick return if possible. * IF( (M.EQ.0).OR.(N.EQ.0).OR. $ ((ALPHA.EQ.ZERO).AND.(BETA.EQ.ONE)) ) $ RETURN * CALL INFOG2L( IA, JA, DESCA, NPROW, NPCOL, MYROW, MYCOL, $ IIA, JJA, IAROW, IACOL ) CALL INFOG2L( IC, JC, DESCC, NPROW, NPCOL, MYROW, MYCOL, $ IIC, JJC, ICROW, ICCOL ) * IROFF = MOD( IA-1, DESCA(MB_) ) ICOFF = MOD( JA-1, DESCA(NB_) ) MP = NUMROC( M+IROFF, DESCA(MB_), MYROW, IAROW, NPROW ) NQ = NUMROC( N+ICOFF, DESCA(NB_), MYCOL, IACOL, NPCOL ) IF( MYROW.EQ.IAROW ) $ MP = MP-IROFF IF( MYCOL.EQ.IACOL ) $ NQ = NQ-ICOFF LDA = DESCA(LLD_) LDC = DESCC(LLD_) * IF( NQ.EQ.1 ) THEN IF( BETA.EQ.ZERO ) THEN IF( ALPHA.EQ.ZERO ) THEN IOFFC = IIC + (JJC-1)*LDC DO 10 I = IOFFC, IOFFC+MP-1 C( I ) = ZERO 10 CONTINUE ELSE IOFFA = IIA + (JJA-1)*LDA IOFFC = IIC + (JJC-1)*LDC DO 20 I = IOFFC, IOFFC+MP-1 C( I ) = ALPHA * A( IOFFA ) IOFFA = IOFFA + 1 20 CONTINUE END IF ELSE IF( ALPHA.EQ.ONE ) THEN IF( BETA.EQ.ONE ) THEN IOFFA = IIA + (JJA-1)*LDA IOFFC = IIC + (JJC-1)*LDC DO 30 I = IOFFC, IOFFC+MP-1 C( I ) = C( I ) + A( IOFFA ) IOFFA = IOFFA + 1 30 CONTINUE ELSE IOFFA = IIA + (JJA-1)*LDA IOFFC = IIC + (JJC-1)*LDC DO 40 I = IOFFC, IOFFC+MP-1 C( I ) = BETA * C( I ) + A( IOFFA ) IOFFA = IOFFA + 1 40 CONTINUE END IF ELSE IF( BETA.EQ.ONE ) THEN IOFFA = IIA + (JJA-1)*LDA IOFFC = IIC + (JJC-1)*LDC DO 50 I = IOFFC, IOFFC+MP-1 C( I ) = C( I ) + ALPHA * A( IOFFA ) IOFFA = IOFFA + 1 50 CONTINUE ELSE IOFFA = IIA + (JJA-1)*LDA IOFFC = IIC + (JJC-1)*LDC DO 60 I = IOFFC, IOFFC+MP-1 C( I ) = BETA * C( I ) + ALPHA * A( IOFFA ) IOFFA = IOFFA + 1 60 CONTINUE END IF END IF ELSE IF( BETA.EQ.ZERO ) THEN IF( ALPHA.EQ.ZERO ) THEN IOFFC = IIC+(JJC-1)*LDC DO 80 J = 1, NQ DO 70 I = IOFFC, IOFFC+MP-1 C( I ) = ZERO 70 CONTINUE IOFFC = IOFFC + LDC 80 CONTINUE ELSE IOFFA = IIA+(JJA-1)*LDA IOFFC = IIC+(JJC-1)*LDC DO 100 J = 1, NQ DO 90 I = IOFFC, IOFFC+MP-1 C( I ) = ALPHA * A( IOFFA ) IOFFA = IOFFA + 1 90 CONTINUE IOFFA = IOFFA + LDA - MP IOFFC = IOFFC + LDC 100 CONTINUE END IF ELSE IF( ALPHA.EQ.ONE ) THEN IF( BETA.EQ.ONE ) THEN IOFFA = IIA+(JJA-1)*LDA IOFFC = IIC+(JJC-1)*LDC DO 120 J = 1, NQ DO 110 I = IOFFC, IOFFC+MP-1 C( I ) = C( I ) + A( IOFFA ) IOFFA = IOFFA + 1 110 CONTINUE IOFFA = IOFFA + LDA - MP IOFFC = IOFFC + LDC 120 CONTINUE ELSE IOFFA = IIA+(JJA-1)*LDA IOFFC = IIC+(JJC-1)*LDC DO 140 J = 1, NQ DO 130 I = IOFFC, IOFFC+MP-1 C( I ) = BETA * C( I ) + A( IOFFA ) IOFFA = IOFFA + 1 130 CONTINUE IOFFA = IOFFA + LDA - MP IOFFC = IOFFC + LDC 140 CONTINUE END IF ELSE IF( BETA.EQ.ONE ) THEN IOFFA = IIA+(JJA-1)*LDA IOFFC = IIC+(JJC-1)*LDC DO 160 J = 1, NQ DO 150 I = IOFFC, IOFFC+MP-1 C( I ) = C( I ) + ALPHA * A( IOFFA ) IOFFA = IOFFA + 1 150 CONTINUE IOFFA = IOFFA + LDA - MP IOFFC = IOFFC + LDC 160 CONTINUE ELSE IOFFA = IIA+(JJA-1)*LDA IOFFC = IIC+(JJC-1)*LDC DO 180 J = 1, NQ DO 170 I = IOFFC, IOFFC+MP-1 C( I ) = BETA * C( I ) + ALPHA * A( IOFFA ) IOFFA = IOFFA + 1 170 CONTINUE IOFFA = IOFFA + LDA - MP IOFFC = IOFFC + LDC 180 CONTINUE END IF END IF END IF * RETURN * * End of PZMATADD * END