..
     .. Array Arguments ..
     ..
  Purpose
  =======
  PDGESV computes the solution to a real system of linear equations
                        sub( A ) * X = sub( B ),
  where sub( A ) = A(IA:IA+N-1,JA:JA+N-1) is an N-by-N distributed
  matrix and X and sub( B ) = B(IB:IB+N-1,JB:JB+NRHS-1) are N-by-NRHS
  distributed matrices.
  The LU decomposition with partial pivoting and row interchanges is
  used to factor sub( A ) as sub( A ) = P * L * U, where P is a permu-
  tation matrix, L is unit lower triangular, and U is upper triangular.
  L and U are stored in sub( A ). The factored form of sub( A ) is then
  used to solve the system of equations sub( A ) * X = sub( B ).
  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
  This routine requires square block decomposition ( MB_A = NB_A ).
  Arguments
  =========
  N       (global input) INTEGER
          The number of rows and columns to be operated on, i.e. the
          order of the distributed submatrix sub( A ). N >= 0.
  NRHS    (global input) INTEGER
          The number of right hand sides, i.e., the number of columns
          of the distributed submatrix sub( B ). NRHS >= 0.
  A       (local input/local output) DOUBLE PRECISION pointer into the
          local memory to an array of dimension (LLD_A,LOCc(JA+N-1)).
          On entry, the local pieces of the N-by-N distributed matrix
          sub( A ) to be factored. On exit, this array contains the
          local pieces of the factors L and U from the factorization
          sub( A ) = P*L*U; the unit diagonal elements of L are not
          stored.
  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.
  IPIV    (local output) INTEGER array, dimension ( LOCr(M_A)+MB_A )
          This array contains the pivoting information.
          IPIV(i) -> The global row local row i was swapped with.
          This array is tied to the distributed matrix A.
  B       (local input/local output) DOUBLE PRECISION pointer into the
          local memory to an array of dimension
          (LLD_B,LOCc(JB+NRHS-1)).  On entry, the right hand side
          distributed matrix sub( B ). On exit, if INFO = 0, sub( B )
          is overwritten by the solution distributed matrix X.
  IB      (global input) INTEGER
          The row index in the global array B indicating the first
          row of sub( B ).
  JB      (global input) INTEGER
          The column index in the global array B indicating the
          first column of sub( B ).
  DESCB   (global and local input) INTEGER array of dimension DLEN_.
          The array descriptor for the distributed matrix B.
  INFO    (global output) INTEGER
          = 0:  successful exit
          < 0:  If the i-th argument is an array and the j-entry had
                an illegal value, then INFO = -(i*100+j), if the i-th
                argument is a scalar and had an illegal value, then
                INFO = -i.
          > 0:  If INFO = K, U(IA+K-1,JA+K-1) is exactly zero.
                The factorization has been completed, but the factor U
                is exactly singular, so the solution could not be
                computed.
  =====================================================================
     .. Parameters ..