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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
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