text: /* ---------------------------------------------------------------------
  *
  *  -- PBLAS auxiliary 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 PB_Cdescribe( int M, int N, int IA, int JA, int * DA, int NPROW,
                     int NPCOL, int MYROW, int MYCOL, int * II, int * JJ,
                     int * LDA, int * IMB, int * INB, int * MB, int * NB,
                     int * PROW, int * PCOL, int * DA0 )
  #else
  void PB_Cdescribe( M, N, IA, JA, DA, NPROW, NPCOL, MYROW, MYCOL, II, JJ,
                     LDA, IMB, INB, MB, NB, PROW, PCOL, DA0 )
  /*
  *  .. Scalar Arguments ..
  */
     int            IA, *II, * IMB, * INB, JA, * JJ, * LDA, M, * MB, MYCOL,
                    MYROW, N, * NB, NPCOL, NPROW, * PCOL, * PROW;
  /*
  *  .. Array Arguments ..
  */
     int            * DA, * DA0;
  #endif
  {
  /*
  *  Purpose
  *  =======
  *
  *  PB_Cdescribe  returns the global descriptor of a submatrix. This rou-
  *  tine also computes the starting local index II, JJ  corresponding  to
  *  the submatrix starting globally at the entry pointed by IA, JA.  This
  *  routine returns the coordinates in the grid of the process owning the
  *  matrix entry of global indexes I, J, namely PROW and PCOL.  The  true
  *  global block sizes IMB, INB, MB and NB are also returned.
  *
  *  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
  *  =========
  *
  *  M       (global input) INTEGER
  *          On entry, M  specifies the number of  rows  being  dealt  out
  *          starting from global index IA. M  is  also the number of rows
  *          of the submatrix of interest. M must be at least zero.
  *
  *  N       (global input) INTEGER
  *          On entry, N  specifies the number of columns being dealt  out
  *          starting from global index JA. N  is  also the number of col-
  *          umns of the submatrix of interest. M must be at least zero.
  *
  *  IA      (global input) INTEGER
  *          On entry, IA specifies  the  global starting row index of the
  *          submatrix. IA must at least zero.
  *
  *  JA      (global input) INTEGER
  *          On entry, JA specifies  the  global  starting column index of
  *          the submatrix. JA must at least zero.
  *
  *  DA      (global and local input) INTEGER array
  *          On entry, DA  is an integer array of dimension DLEN_. This is
  *          the array descriptor of the underlying matrix.
  *
  *  NPROW   (global input) INTEGER
  *          On entry,  NPROW   specifies the total number of process rows
  *          over which the matrix is distributed.  NPROW must be at least
  *          one.
  *
  *  NPCOL   (global input) INTEGER
  *          On entry, NPCOL specifies the total number of process columns
  *          over which the matrix is distributed.  NPCOL must be at least
  *          one.
  *
  *  MYROW   (local input) INTEGER
  *          On entry,  MYROW  specifies the row coordinate of the process
  *          whose local index  II  is determined.  MYROW must be at least
  *          zero and strictly less than NPROW.
  *
  *  II      (local output) INTEGER
  *          On exit, II  specifies the  local  starting  row index of the
  *          submatrix. On exit, II is at least zero.
  *
  *  JJ      (local output) INTEGER
  *          On exit, JJ  specifies the local starting column index of the
  *          submatrix. On exit, JJ is at least zero.
  *
  *  LDA     (local output) INTEGER
  *          On exit, LDA specifies the local leading dimension of the lo-
  *          cal array containing the distributed matrix entries. LDA must
  *          be at least one.
  *
  *  IMB     (global output) INTEGER
  *          On exit, IMB  specifies the true global number of matrix rows
  *          of the first block, if M rows are given out starting from the
  *          global index IA. If M is equal zero, IMB is set to zero.
  *
  *  INB     (global output) INTEGER
  *          On exit, INB  specifies the true global number of matrix col-
  *          umns of the first block, if N columns are given out  starting
  *          from the global index JA. If N is equal zero, INB  is  set to
  *          zero.
  *
  *  MB      (global output) INTEGER
  *          On exit,  MB specifies the size of the blocks used to  parti-
  *          tion the matrix rows. MB is at least one.
  *
  *  NB      (global output) INTEGER
  *          On exit,  NB specifies the size of the blocks used to  parti-
  *          tion the matrix columns. NB is at least one.
  *
  *  PROW    (global output) INTEGER
  *          On exit,  PROW  specifies  the  row coordinate of the process
  *          that possesses the first row of the submatrix.  On exit, PROW
  *          is -1 if DESC( RSRC_ )  is -1 on input, and,  at  least  zero
  *          and strictly less than NPROW otherwise.
  *
  *  PCOL    (global output) INTEGER
  *          On exit, PCOL  specifies the column coordinate of the process
  *          that possesses the first column of the  submatrix.  On  exit,
  *          PCOL is -1 if DESC( CSRC_ )  is -1 on input, and,  at   least
  *          zero and strictly less than NPCOL otherwise.
  *
  *  DA0     (global and local output) INTEGER array
  *          On exit, DA0 is an integer array of dimension DLEN_.  This is
  *          the array descriptor of the submatrix A(IA:IA+M-1,JA:JA+N-1).
  *
  *  -- Written on April 1, 1998 by
  *     Antoine Petitet, University of Tennessee, Knoxville 37996, USA.
  *
  *  ---------------------------------------------------------------------
  */
  /* ..
  *  .. Executable Statements ..
  *
  */
     *MB = DA[MB_]; Mfirstnb( *IMB, M, IA, DA[IMB_], *MB );
     *NB = DA[NB_]; Mfirstnb( *INB, N, JA, DA[INB_], *NB ); *LDA = DA[LLD_];
     Minfog2l( IA, JA, DA, NPROW, NPCOL, MYROW, MYCOL, *II, *JJ, *PROW, *PCOL );
     MDescSet( DA0, M, N, *IMB, *INB, *MB, *NB, *PROW, *PCOL, DA[CTXT_], *LDA );
  /*
  *  End of PB_Cdescribe
  */
  }
  