SUBROUTINE PCLACGV( N, X, IX, JX, DESCX, INCX ) * * -- ScaLAPACK auxiliary routine (version 1.5) -- * University of Tennessee, Knoxville, Oak Ridge National Laboratory, * and University of California, Berkeley. * May 1, 1997 * * .. Scalar Arguments .. INTEGER INCX, IX, JX, N * .. * .. Array Arguments .. INTEGER DESCX( * ) COMPLEX X( * ) * .. * * Purpose * ======= * * PCLACGV conjugates a complex vector of length N, sub( X ), where * sub( X ) denotes X(IX,JX:JX+N-1) if INCX = DESCX( M_ ) and * X(IX:IX+N-1,JX) if INCX = 1, and * * 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 * * Because vectors may be viewed as a subclass of matrices, a * distributed vector is considered to be a distributed matrix. * * Arguments * ========= * * N (global input) INTEGER * The length of the distributed vector sub( X ). * * X (local input/local output) COMPLEX pointer into the * local memory to an array of dimension (LLD_X,*). * On entry the vector to be conjugated * x( i ) = X(IX+(JX-1)*M_X +(i-1)*INCX ), 1 <= i <= N. * On exit the conjugated vector. * * IX (global input) INTEGER * The row index in the global array X indicating the first * row of sub( X ). * * JX (global input) INTEGER * The column index in the global array X indicating the * first column of sub( X ). * * DESCX (global and local input) INTEGER array of dimension DLEN_. * The array descriptor for the distributed matrix X. * * INCX (global input) INTEGER * The global increment for the elements of X. Only two values * of INCX are supported in this version, namely 1 and M_X. * INCX must not be zero. * * ===================================================================== * * .. 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 ) * .. * .. Local Scalars .. INTEGER I, ICOFFX, ICTXT, IIX, IOFFX, IROFFX, IXCOL, $ IXROW, JJX, LDX, MYCOL, MYROW, NP, NPCOL, $ NPROW, NQ * .. * .. External Subroutines .. EXTERNAL BLACS_GRIDINFO, INFOG2L * .. * .. External Functions .. INTEGER NUMROC EXTERNAL NUMROC * .. * .. Intrinsic Functions .. INTRINSIC CONJG, MOD * .. * .. Executable Statements .. * * Get grid parameters. * ICTXT = DESCX( CTXT_ ) CALL BLACS_GRIDINFO( ICTXT, NPROW, NPCOL, MYROW, MYCOL ) * * Figure local indexes * CALL INFOG2L( IX, JX, DESCX, NPROW, NPCOL, MYROW, MYCOL, $ IIX, JJX, IXROW, IXCOL ) * LDX = DESCX( LLD_ ) IF( INCX.EQ.DESCX( M_ ) ) THEN * * sub( X ) is rowwise distributed. * IF( MYROW.NE.IXROW ) $ RETURN ICOFFX = MOD( JX-1, DESCX( NB_ ) ) NQ = NUMROC( N+ICOFFX, DESCX( NB_ ), MYCOL, IXCOL, NPCOL ) IF( MYCOL.EQ.IXCOL ) $ NQ = NQ - ICOFFX * IF( NQ.GT.0 ) THEN IOFFX = IIX+(JJX-1)*LDX DO 10 I = 1, NQ X( IOFFX ) = CONJG( X( IOFFX ) ) IOFFX = IOFFX + LDX 10 CONTINUE END IF * ELSE IF( INCX.EQ.1 ) THEN * * sub( X ) is columnwise distributed. * IF( MYCOL.NE.IXCOL ) $ RETURN IROFFX = MOD( IX-1, DESCX( MB_ ) ) NP = NUMROC( N+IROFFX, DESCX( MB_ ), MYROW, IXROW, NPROW ) IF( MYROW.EQ.IXROW ) $ NP = NP - IROFFX * IF( NP.GT.0 ) THEN IOFFX = IIX+(JJX-1)*LDX DO 20 I = IOFFX, IOFFX+NP-1 X( I ) = CONJG( X( I ) ) 20 CONTINUE END IF * END IF * RETURN * * End of PCLACGV * END