/* --------------------------------------------------------------------- * * -- PBLAS routine (version 2.0) -- * University of Tennessee, Knoxville, Oak Ridge National Laboratory, * and University of California, Berkeley. * April 1, 1998 * * --------------------------------------------------------------------- */ /* * Include files */ #include "pblas.h" #include "PBpblas.h" #include "PBtools.h" #include "PBblacs.h" #include "PBblas.h" #ifdef __STDC__ void pcamax_( int * N, float * AMAX, int * INDX, float * X, int * IX, int * JX, int * DESCX, int * INCX ) #else void pcamax_( N, AMAX, INDX, X, IX, JX, DESCX, INCX ) /* * .. Scalar Arguments .. */ int * INCX, * INDX, * IX, * JX, * N; float * AMAX; /* * .. Array Arguments .. */ int * DESCX; float * X; #endif { /* * Purpose * ======= * * PCAMAX computes the global index of the maximum element in absolute * value of a subvector sub( X ). The global index is returned in INDX * and the value of that element is returned in AMAX, * * where * * sub( X ) denotes X(IX,JX:JX+N-1) if INCX = M_X, * X(IX:IX+N-1,JX) if INCX = 1 and INCX <> M_X. * * Notes * ===== * * A description vector is associated with each 2D block-cyclicly dis- * tributed matrix. This vector stores the information required to * establish the mapping between a matrix entry and its corresponding * process and memory location. * * In the following comments, the character _ should be read as * "of the distributed matrix". Let A be a generic term for any 2D * block cyclicly distributed matrix. Its description vector is DESC_A: * * NOTATION STORED IN EXPLANATION * ---------------- --------------- ------------------------------------ * DTYPE_A (global) DESCA[ DTYPE_ ] The descriptor type. * CTXT_A (global) DESCA[ CTXT_ ] The BLACS context handle, indicating * the NPROW x NPCOL BLACS process grid * A is distributed over. The context * itself is global, but the handle * (the integer value) may vary. * M_A (global) DESCA[ M_ ] The number of rows in the distribu- * ted matrix A, M_A >= 0. * N_A (global) DESCA[ N_ ] The number of columns in the distri- * buted matrix A, N_A >= 0. * IMB_A (global) DESCA[ IMB_ ] The number of rows of the upper left * block of the matrix A, IMB_A > 0. * INB_A (global) DESCA[ INB_ ] The number of columns of the upper * left block of the matrix A, * INB_A > 0. * MB_A (global) DESCA[ MB_ ] The blocking factor used to distri- * bute the last M_A-IMB_A rows of A, * MB_A > 0. * NB_A (global) DESCA[ NB_ ] The blocking factor used to distri- * bute the last N_A-INB_A columns of * A, NB_A > 0. * RSRC_A (global) DESCA[ RSRC_ ] The process row over which the first * row of the matrix A is distributed, * NPROW > RSRC_A >= 0. * CSRC_A (global) DESCA[ CSRC_ ] The process column over which the * first column of A is distributed. * NPCOL > CSRC_A >= 0. * LLD_A (local) DESCA[ LLD_ ] The leading dimension of the local * array storing the local blocks of * the distributed matrix A, * IF( Lc( 1, N_A ) > 0 ) * LLD_A >= MAX( 1, Lr( 1, M_A ) ) * ELSE * LLD_A >= 1. * * Let K be the number of rows of a matrix A starting at the global in- * dex IA,i.e, A( IA:IA+K-1, : ). Lr( IA, K ) denotes the number of rows * that the process of row coordinate MYROW ( 0 <= MYROW < NPROW ) would * receive if these K rows were distributed over NPROW processes. If K * is the number of columns of a matrix A starting at the global index * JA, i.e, A( :, JA:JA+K-1, : ), Lc( JA, K ) denotes the number of co- * lumns that the process MYCOL ( 0 <= MYCOL < NPCOL ) would receive if * these K columns were distributed over NPCOL processes. * * The values of Lr() and Lc() may be determined via a call to the func- * tion PB_Cnumroc: * Lr( IA, K ) = PB_Cnumroc( K, IA, IMB_A, MB_A, MYROW, RSRC_A, NPROW ) * Lc( JA, K ) = PB_Cnumroc( K, JA, INB_A, NB_A, MYCOL, CSRC_A, NPCOL ) * * Arguments * ========= * * N (global input) INTEGER * On entry, N specifies the length of the subvector sub( X ). * N must be at least zero. * * AMAX (global output) COMPLEX array * On exit, AMAX specifies the largest entry in absolute value * of the subvector sub( X ) only in its scope (See below for * further details). * * INDX (global output) INTEGER * On exit, INDX specifies the global index of the maximum ele- * ment in absolute value of the subvector sub( X ) only in its * scope (See below for further details). * * X (local input) COMPLEX array * On entry, X is an array of dimension (LLD_X, Kx), where LLD_X * is at least MAX( 1, Lr( 1, IX ) ) when INCX = M_X and * MAX( 1, Lr( 1, IX+N-1 ) ) otherwise, and, Kx is at least * Lc( 1, JX+N-1 ) when INCX = M_X and Lc( 1, JX ) otherwise. * Before entry, this array contains the local entries of the * matrix X. * * IX (global input) INTEGER * On entry, IX specifies X's global row index, which points to * the beginning of the submatrix sub( X ). * * JX (global input) INTEGER * On entry, JX specifies X's global column index, which points * to the beginning of the submatrix sub( X ). * * DESCX (global and local input) INTEGER array * On entry, DESCX is an integer array of dimension DLEN_. This * is the array descriptor for the matrix X. * * INCX (global input) INTEGER * On entry, INCX specifies 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. * * Further Details * =============== * * When the result of a vector-oriented PBLAS call is a scalar, this * scalar is set only within the process scope which owns the vector(s) * being operated on. Let sub( X ) be a generic term for the input vec- * tor(s). Then, the processes owning the correct the answer is determi- * ned as follows: if an operation involves more than one vector, the * processes receiving the result will be the union of the following set * of processes for each vector: * * If N = 1, M_X = 1 and INCX = 1, then one cannot determine if a pro- * cess row or process column owns the vector operand, therefore only * the process owning sub( X ) receives the correct result; * * If INCX = M_X, then sub( X ) is a vector distributed over a process * row. Each process in this row receives the result; * * If INCX = 1, then sub( X ) is a vector distributed over a process * column. Each process in this column receives the result; * * -- Written on April 1, 1998 by * Antoine Petitet, University of Tennessee, Knoxville 37996, USA. * * --------------------------------------------------------------------- */ /* * .. Local Scalars .. */ char cbtop, cctop, rbtop, rctop; int Xcol, Xgindx, Xi, Xii, Ximb, Xinb, Xj, Xjj, Xlindx, Xld, Xmb, Xnb, Xnp, Xnq, Xrow, Xsrc, ctxt, dist, dst, idumm, info, k, maxpos, mycol, mydist, myrow, npcol, nprow, src, size; PBTYP_T * type; /* * .. Local Arrays .. */ char * Xptr; int Xd[DLEN_]; cmplx work[4]; /* .. * .. Executable Statements .. * */ PB_CargFtoC( *IX, *JX, DESCX, &Xi, &Xj, Xd ); #ifndef NO_ARGCHK /* * Test the input parameters */ Cblacs_gridinfo( ( ctxt = Xd[CTXT_] ), &nprow, &npcol, &myrow, &mycol ); if( !( info = ( ( nprow == -1 ) ? -( 701 + CTXT_ ) : 0 ) ) ) PB_Cchkvec( ctxt, "PCAMAX", "X", *N, 1, Xi, Xj, Xd, *INCX, 7, &info ); if( info ) { PB_Cabort( ctxt, "PCAMAX", info ); return; } #endif /* * Initialize INDX and AMAX */ *INDX = 0; AMAX[REAL_PART] = ZERO; AMAX[IMAG_PART] = ZERO; /* * Quick return if possible */ if( *N == 0 ) return; /* * Retrieve process grid information */ #ifdef NO_ARGCHK Cblacs_gridinfo( ( ctxt = Xd[CTXT_] ), &nprow, &npcol, &myrow, &mycol ); #endif /* * Retrieve sub( X )'s local information: Xii, Xjj, Xrow, Xcol */ PB_Cinfog2l( Xi, Xj, Xd, nprow, npcol, myrow, mycol, &Xii, &Xjj, &Xrow, &Xcol ); /* * Handle degenerate case separately, sub( X )'s scope is just one process */ if( ( *INCX == 1 ) && ( Xd[M_] == 1 ) && ( *N == 1 ) ) { /* * Make sure I own some data and compute INDX and AMAX */ if( ( ( myrow == Xrow ) || ( Xrow < 0 ) ) && ( ( mycol == Xcol ) || ( Xcol < 0 ) ) ) { *INDX = *JX; type = PB_Cctypeset(); Xptr = Mptr( ((char *) X), Xii, Xjj, Xd[LLD_], type->size ); AMAX[REAL_PART] = ((float*)(Xptr))[REAL_PART]; AMAX[IMAG_PART] = ((float*)(Xptr))[IMAG_PART]; } return; } else if( *INCX == Xd[M_] ) { /* * sub( X ) resides in (a) process row(s) */ if( ( myrow == Xrow ) || ( Xrow < 0 ) ) { rctop = *PB_Ctop( &ctxt, COMBINE, ROW, TOP_GET ); if( ( rctop == CTOP_DEFAULT ) || ( rctop == CTOP_TREE1 ) ) { /* * Inline the 1-tree combine for communication savings */ Xinb = Xd[INB_ ]; Xnb = Xd[NB_ ]; Xsrc = Xd[CSRC_]; Xnq = PB_Cnumroc( *N, Xj, Xinb, Xnb, mycol, Xsrc, npcol ); /* * Make sure I own some data and compute local INDX and AMAX */ if( Xnq > 0 ) { Xld = Xd[LLD_]; type = PB_Cctypeset(); size = type->size; Xlindx = Xjj - 1 + icamax_( &Xnq, Mptr( ((char *) X), Xii, Xjj, Xld, size ), &Xld ); Mindxl2g( Xgindx, Xlindx, Xinb, Xnb, mycol, Xsrc, npcol ); Xptr = Mptr( ((char *) X), Xii, Xlindx, Xld, size ); work[0][REAL_PART] = ((float*)(Xptr))[REAL_PART]; work[0][IMAG_PART] = ((float*)(Xptr))[IMAG_PART]; work[1][REAL_PART] = ((float )( Xgindx+1 )); work[1][IMAG_PART] = ZERO; } else { work[0][REAL_PART] = ZERO; work[0][IMAG_PART] = ZERO; work[1][REAL_PART] = ZERO; work[1][IMAG_PART] = ZERO; } /* * Combine the local results using a 1-tree topology within process column 0 * if npcol > 1 or Xcol >= 0, i.e sub( X ) is distributed. */ if( ( npcol >= 2 ) && ( Xcol >= 0 ) ) { mydist = mycol; k = 1; l_10: if( mydist & 1 ) { dist = k * ( mydist - 1 ); dst = MPosMod( dist, npcol ); Ccgesd2d( ctxt, 2, 1, ((char*)work), 2, myrow, dst ); goto l_20; } else { dist = mycol + k; src = MPosMod( dist, npcol ); if( mycol < src ) { Ccgerv2d( ctxt, 2, 1, ((char*) work[2]), 2, myrow, src ); if( ( ABS( work[0][REAL_PART] ) + ABS( work[0][IMAG_PART] ) ) < ( ABS( work[2][REAL_PART] ) + ABS( work[2][IMAG_PART] ) ) ) { work[0][REAL_PART] = work[2][REAL_PART]; work[0][IMAG_PART] = work[2][IMAG_PART]; work[1][REAL_PART] = work[3][REAL_PART]; } } mydist >>= 1; } k <<= 1; if( k < npcol ) goto l_10; l_20: /* * Process column 0 broadcasts the combined values of INDX and AMAX within * their process row. */ rbtop = *PB_Ctop( &ctxt, BCAST, ROW, TOP_GET ); if( mycol == 0 ) { Ccgebs2d( ctxt, ROW, &rbtop, 2, 1, ((char*)work), 2 ); } else { Ccgebr2d( ctxt, ROW, &rbtop, 2, 1, ((char*)work), 2, myrow, 0 ); } } /* * Set INDX and AMAX to the replicated answers contained in work. If AMAX is * zero, then select a coherent INDX. */ AMAX[REAL_PART] = work[0][REAL_PART]; AMAX[IMAG_PART] = work[0][IMAG_PART]; *INDX = ( ( ( AMAX[REAL_PART] == ZERO ) && ( AMAX[IMAG_PART] == ZERO ) ) ? ( *JX ) : ( (int)(work[1][REAL_PART]) ) ); } else { /* * Otherwise use the current topology settings to combine the results */ Xinb = Xd[INB_ ]; Xnb = Xd[NB_ ]; Xsrc = Xd[CSRC_]; Xnq = PB_Cnumroc( *N, Xj, Xinb, Xnb, mycol, Xsrc, npcol ); /* * Make sure I own some data and compute local INDX and AMAX */ if( Xnq > 0 ) { /* * Compute the local maximum and its corresponding local index */ Xld = Xd[LLD_]; type = PB_Cctypeset(); size = type->size; Xlindx = Xjj - 1 + icamax_( &Xnq, Mptr( ((char *) X), Xii, Xjj, Xld, size ), &Xld ); Xptr = Mptr( ((char *) X), Xii, Xlindx, Xld, size ); AMAX[REAL_PART] = ((float*)(Xptr))[REAL_PART]; AMAX[IMAG_PART] = ((float*)(Xptr))[IMAG_PART]; } else { AMAX[REAL_PART] = ZERO; AMAX[IMAG_PART] = ZERO; } if( Xcol >= 0 ) { /* * Combine leave on all the local maximum if Xcol >= 0, i.e sub( X ) is * distributed */ Ccgamx2d( ctxt, ROW, &rctop, 1, 1, ((char*)AMAX), 1, &idumm, &maxpos, 1, -1, mycol ); /* * Broadcast the corresponding global index */ if( ( AMAX[REAL_PART] != ZERO ) || ( AMAX[IMAG_PART] != ZERO ) ) { rbtop = *PB_Ctop( &ctxt, BCAST, ROW, TOP_GET ); if( mycol == maxpos ) { Mindxl2g( Xgindx, Xlindx, Xinb, Xnb, mycol, Xsrc, npcol ); *INDX = Xgindx + 1; Cigebs2d( ctxt, ROW, &rbtop, 1, 1, ((char*)INDX), 1 ); } else { Cigebr2d( ctxt, ROW, &rbtop, 1, 1, ((char*)INDX), 1, myrow, maxpos ); } } else { /* * If AMAX is zero, then select a coherent INDX. */ *INDX = *JX; } } else { /* * sub( X ) is not distributed. If AMAX is zero, then select a coherent INDX. */ *INDX = ( ( ( AMAX[REAL_PART] == ZERO ) && ( AMAX[IMAG_PART] == ZERO ) ) ? ( *JX ) : Xlindx + 1 ); } } } return; } else { /* * sub( X ) resides in (a) process column(s) */ if( ( mycol == Xcol ) || ( Xcol < 0 ) ) { cctop = *PB_Ctop( &ctxt, COMBINE, COLUMN, TOP_GET ); if( ( cctop == CTOP_DEFAULT ) || ( cctop == CTOP_TREE1 ) ) { /* * Inline the 1-tree combine for communication savings */ Ximb = Xd[IMB_ ]; Xmb = Xd[MB_ ]; Xsrc = Xd[RSRC_]; Xnp = PB_Cnumroc( *N, Xi, Ximb, Xmb, myrow, Xsrc, nprow ); /* * Make sure I own some data and compute local INDX and AMAX */ if( Xnp > 0 ) { Xld = Xd[LLD_]; type = PB_Cctypeset(); size = type->size; Xlindx = Xii - 1 + icamax_( &Xnp, Mptr( ((char *)X), Xii, Xjj, Xld, size ), INCX ); Mindxl2g( Xgindx, Xlindx, Ximb, Xmb, myrow, Xsrc, nprow ); Xptr = Mptr( ((char *) X), Xlindx, Xjj, Xld, size ); work[0][REAL_PART] = ((float*)(Xptr))[REAL_PART]; work[0][IMAG_PART] = ((float*)(Xptr))[IMAG_PART]; work[1][REAL_PART] = ((float )( Xgindx+1 )); work[1][IMAG_PART] = ZERO; } else { work[0][REAL_PART] = ZERO; work[0][IMAG_PART] = ZERO; work[1][REAL_PART] = ZERO; work[1][IMAG_PART] = ZERO; } /* * Combine the local results using a 1-tree topology within process row 0 * if nprow > 1 or Xrow >= 0, i.e sub( X ) is distributed. */ if( ( nprow >= 2 ) && ( Xrow >= 0 ) ) { mydist = myrow; k = 1; l_30: if( mydist & 1 ) { dist = k * ( mydist - 1 ); dst = MPosMod( dist, nprow ); Ccgesd2d( ctxt, 2, 1, ((char*)work), 2, dst, mycol ); goto l_40; } else { dist = myrow + k; src = MPosMod( dist, nprow ); if( myrow < src ) { Ccgerv2d( ctxt, 2, 1, ((char*) work[2]), 2, src, mycol ); if( ( ABS( work[0][REAL_PART] ) + ABS( work[0][IMAG_PART] ) ) < ( ABS( work[2][REAL_PART] ) + ABS( work[2][IMAG_PART] ) ) ) { work[0][REAL_PART] = work[2][REAL_PART]; work[0][IMAG_PART] = work[2][IMAG_PART]; work[1][REAL_PART] = work[3][REAL_PART]; } } mydist >>= 1; } k <<= 1; if( k < nprow ) goto l_30; l_40: /* * Process row 0 broadcasts the combined values of INDX and AMAX within their * process column. */ cbtop = *PB_Ctop( &ctxt, BCAST, COLUMN, TOP_GET ); if( myrow == 0 ) { Ccgebs2d( ctxt, COLUMN, &cbtop, 2, 1, ((char*)work), 2 ); } else { Ccgebr2d( ctxt, COLUMN, &cbtop, 2, 1, ((char*)work), 2, 0, mycol ); } } /* * Set INDX and AMAX to the replicated answers contained in work. If AMAX is * zero, then select a coherent INDX. */ AMAX[REAL_PART] = work[0][REAL_PART]; AMAX[IMAG_PART] = work[0][IMAG_PART]; *INDX = ( ( ( AMAX[REAL_PART] == ZERO ) && ( AMAX[IMAG_PART] == ZERO ) ) ? ( *IX ) : ( (int)(work[1][REAL_PART]) ) ); } else { /* * Otherwise use the current topology settings to combine the results */ Ximb = Xd[IMB_ ]; Xmb = Xd[MB_ ]; Xsrc = Xd[RSRC_]; Xnp = PB_Cnumroc( *N, Xi, Ximb, Xmb, myrow, Xsrc, nprow ); /* * Make sure I own some data and compute local INDX and AMAX */ if( Xnp > 0 ) { /* * Compute the local maximum and its corresponding local index */ Xld = Xd[LLD_]; type = PB_Cctypeset(); size = type->size; Xlindx = Xii - 1 + icamax_( &Xnp, Mptr( ((char *) X), Xii, Xjj, Xld, size ), INCX ); Xptr = Mptr( ((char *) X), Xlindx, Xjj, Xld, size ); AMAX[REAL_PART] = ((float*)(Xptr))[REAL_PART]; AMAX[IMAG_PART] = ((float*)(Xptr))[IMAG_PART]; } else { AMAX[REAL_PART] = ZERO; AMAX[IMAG_PART] = ZERO; } if( Xrow >= 0 ) { /* * Combine leave on all the local maximum if Xrow >= 0, i.e sub( X ) is * distributed. */ Ccgamx2d( ctxt, COLUMN, &cctop, 1, 1, ((char*)AMAX), 1, &maxpos, &idumm, 1, -1, mycol ); /* * Broadcast the corresponding global index */ if( ( AMAX[REAL_PART] != ZERO ) || ( AMAX[IMAG_PART] != ZERO ) ) { cbtop = *PB_Ctop( &ctxt, BCAST, COLUMN, TOP_GET ); if( myrow == maxpos ) { Mindxl2g( Xgindx, Xlindx, Ximb, Xmb, myrow, Xsrc, nprow ); *INDX = Xgindx + 1; Cigebs2d( ctxt, COLUMN, &cbtop, 1, 1, ((char*)INDX), 1 ); } else { Cigebr2d( ctxt, COLUMN, &cbtop, 1, 1, ((char*)INDX), 1, maxpos, mycol ); } } else { /* * If AMAX is zero, then select a coherent INDX. */ *INDX = *IX; } } else { /* * sub( X ) is not distributed. If AMAX is zero, then select a coherent INDX. */ *INDX = ( ( ( AMAX[REAL_PART] == ZERO ) && ( AMAX[IMAG_PART] == ZERO ) ) ? ( *IX ) : Xlindx + 1 ); } } } return; } /* * End of PCAMAX */ }