1 SUBROUTINE PZLACGV( N, X, IX, JX, DESCX, INCX ) 2* 3* -- ScaLAPACK auxiliary routine (version 1.7) -- 4* University of Tennessee, Knoxville, Oak Ridge National Laboratory, 5* and University of California, Berkeley. 6* May 1, 1997 7* 8* .. Scalar Arguments .. 9 INTEGER INCX, IX, JX, N 10* .. 11* .. Array Arguments .. 12 INTEGER DESCX( * ) 13 COMPLEX*16 X( * ) 14* .. 15* 16* Purpose 17* ======= 18* 19* PZLACGV conjugates a complex vector of length N, sub( X ), where 20* sub( X ) denotes X(IX,JX:JX+N-1) if INCX = DESCX( M_ ) and 21* X(IX:IX+N-1,JX) if INCX = 1, and 22* 23* Notes 24* ===== 25* 26* Each global data object is described by an associated description 27* vector. This vector stores the information required to establish 28* the mapping between an object element and its corresponding process 29* and memory location. 30* 31* Let A be a generic term for any 2D block cyclicly distributed array. 32* Such a global array has an associated description vector DESCA. 33* In the following comments, the character _ should be read as 34* "of the global array". 35* 36* NOTATION STORED IN EXPLANATION 37* --------------- -------------- -------------------------------------- 38* DTYPE_A(global) DESCA( DTYPE_ )The descriptor type. In this case, 39* DTYPE_A = 1. 40* CTXT_A (global) DESCA( CTXT_ ) The BLACS context handle, indicating 41* the BLACS process grid A is distribu- 42* ted over. The context itself is glo- 43* bal, but the handle (the integer 44* value) may vary. 45* M_A (global) DESCA( M_ ) The number of rows in the global 46* array A. 47* N_A (global) DESCA( N_ ) The number of columns in the global 48* array A. 49* MB_A (global) DESCA( MB_ ) The blocking factor used to distribute 50* the rows of the array. 51* NB_A (global) DESCA( NB_ ) The blocking factor used to distribute 52* the columns of the array. 53* RSRC_A (global) DESCA( RSRC_ ) The process row over which the first 54* row of the array A is distributed. 55* CSRC_A (global) DESCA( CSRC_ ) The process column over which the 56* first column of the array A is 57* distributed. 58* LLD_A (local) DESCA( LLD_ ) The leading dimension of the local 59* array. LLD_A >= MAX(1,LOCr(M_A)). 60* 61* Let K be the number of rows or columns of a distributed matrix, 62* and assume that its process grid has dimension p x q. 63* LOCr( K ) denotes the number of elements of K that a process 64* would receive if K were distributed over the p processes of its 65* process column. 66* Similarly, LOCc( K ) denotes the number of elements of K that a 67* process would receive if K were distributed over the q processes of 68* its process row. 69* The values of LOCr() and LOCc() may be determined via a call to the 70* ScaLAPACK tool function, NUMROC: 71* LOCr( M ) = NUMROC( M, MB_A, MYROW, RSRC_A, NPROW ), 72* LOCc( N ) = NUMROC( N, NB_A, MYCOL, CSRC_A, NPCOL ). 73* An upper bound for these quantities may be computed by: 74* LOCr( M ) <= ceil( ceil(M/MB_A)/NPROW )*MB_A 75* LOCc( N ) <= ceil( ceil(N/NB_A)/NPCOL )*NB_A 76* 77* Because vectors may be viewed as a subclass of matrices, a 78* distributed vector is considered to be a distributed matrix. 79* 80* Arguments 81* ========= 82* 83* N (global input) INTEGER 84* The length of the distributed vector sub( X ). 85* 86* X (local input/local output) COMPLEX*16 pointer into the 87* local memory to an array of dimension (LLD_X,*). 88* On entry the vector to be conjugated 89* x( i ) = X(IX+(JX-1)*M_X +(i-1)*INCX ), 1 <= i <= N. 90* On exit the conjugated vector. 91* 92* IX (global input) INTEGER 93* The row index in the global array X indicating the first 94* row of sub( X ). 95* 96* JX (global input) INTEGER 97* The column index in the global array X indicating the 98* first column of sub( X ). 99* 100* DESCX (global and local input) INTEGER array of dimension DLEN_. 101* The array descriptor for the distributed matrix X. 102* 103* INCX (global input) INTEGER 104* The global increment for the elements of X. Only two values 105* of INCX are supported in this version, namely 1 and M_X. 106* INCX must not be zero. 107* 108* ===================================================================== 109* 110* .. Parameters .. 111 INTEGER BLOCK_CYCLIC_2D, CSRC_, CTXT_, DLEN_, DTYPE_, 112 $ LLD_, MB_, M_, NB_, N_, RSRC_ 113 PARAMETER ( BLOCK_CYCLIC_2D = 1, DLEN_ = 9, DTYPE_ = 1, 114 $ CTXT_ = 2, M_ = 3, N_ = 4, MB_ = 5, NB_ = 6, 115 $ RSRC_ = 7, CSRC_ = 8, LLD_ = 9 ) 116* .. 117* .. Local Scalars .. 118 INTEGER I, ICOFFX, ICTXT, IIX, IOFFX, IROFFX, IXCOL, 119 $ IXROW, JJX, LDX, MYCOL, MYROW, NP, NPCOL, 120 $ NPROW, NQ 121* .. 122* .. External Subroutines .. 123 EXTERNAL BLACS_GRIDINFO, INFOG2L 124* .. 125* .. External Functions .. 126 INTEGER NUMROC 127 EXTERNAL NUMROC 128* .. 129* .. Intrinsic Functions .. 130 INTRINSIC DCONJG, MOD 131* .. 132* .. Executable Statements .. 133* 134* Get grid parameters. 135* 136 ICTXT = DESCX( CTXT_ ) 137 CALL BLACS_GRIDINFO( ICTXT, NPROW, NPCOL, MYROW, MYCOL ) 138* 139* Figure local indexes 140* 141 CALL INFOG2L( IX, JX, DESCX, NPROW, NPCOL, MYROW, MYCOL, 142 $ IIX, JJX, IXROW, IXCOL ) 143* 144 LDX = DESCX( LLD_ ) 145 IF( INCX.EQ.DESCX( M_ ) ) THEN 146* 147* sub( X ) is rowwise distributed. 148* 149 IF( MYROW.NE.IXROW ) 150 $ RETURN 151 ICOFFX = MOD( JX-1, DESCX( NB_ ) ) 152 NQ = NUMROC( N+ICOFFX, DESCX( NB_ ), MYCOL, IXCOL, NPCOL ) 153 IF( MYCOL.EQ.IXCOL ) 154 $ NQ = NQ - ICOFFX 155* 156 IF( NQ.GT.0 ) THEN 157 IOFFX = IIX+(JJX-1)*LDX 158 DO 10 I = 1, NQ 159 X( IOFFX ) = DCONJG( X( IOFFX ) ) 160 IOFFX = IOFFX + LDX 161 10 CONTINUE 162 END IF 163* 164 ELSE IF( INCX.EQ.1 ) THEN 165* 166* sub( X ) is columnwise distributed. 167* 168 IF( MYCOL.NE.IXCOL ) 169 $ RETURN 170 IROFFX = MOD( IX-1, DESCX( MB_ ) ) 171 NP = NUMROC( N+IROFFX, DESCX( MB_ ), MYROW, IXROW, NPROW ) 172 IF( MYROW.EQ.IXROW ) 173 $ NP = NP - IROFFX 174* 175 IF( NP.GT.0 ) THEN 176 IOFFX = IIX+(JJX-1)*LDX 177 DO 20 I = IOFFX, IOFFX+NP-1 178 X( I ) = DCONJG( X( I ) ) 179 20 CONTINUE 180 END IF 181* 182 END IF 183* 184 RETURN 185* 186* End of PZLACGV 187* 188 END 189