psblas3/docs/pdf/toolsrout.tex

\section{Data management routines}
\label{sec:toolsrout}


%
%%   psb_cdall %%
%
\subroutine{psb\_cdall}{Allocates a communication descriptor}

\syntax{call psb\_cdall}{m, n, parts, icontxt, desc\_a, info}
\syntax*{call psb\_cdall}{m, v, icontxt, desc\_a, info, flag}

This subroutine initializes the communication descriptor associated
with an index space. It takes two forms depending on whether the user
specifies the domain partitioning through a subroutine or through a vector
\begin{description}
\item[\bf  First Form: On Entry ]
\item[m] the number of rows of the problem.\\
Scope:{\bf global}.\\
Type:{\bf required}.\\
Specified as: an integer value.
\item[n] the number of columns of the problem.\\
Scope:{\bf global}.\\
Type:{\bf required}.\\
Specified as: an integer value. Currently constrained to be  $m=n$.
\item[parts] the subroutine that defines the partitioning scheme.\\
Scope:{\bf global}.\\
Type:{\bf required}.\\
Specified as: a subroutine. 
\item[icontxt] the communication context.\\
Scope:{\bf global}.\\
Type:{\bf required}.\\
Specified as: an integer value.
\end{description}
\begin{description}
\item[\bf  Second Form: On Entry ]
\item[m] the size of the index space.\\
Scope:{\bf global}.\\
Type:{\bf required}.\\
Specified as: an integer value $m>0$.
\item[v] Data allocation: each index $i\in \{1\dots m\}$ is allocated
  to process $v(i)$.
Scope:{\bf global}.\\
Type:{\bf required}.\\
Specified as: an integer array of size $m$. 
\item[icontxt] the communication context.\\
Scope:{\bf global}.\\
Type:{\bf required}.\\
Specified as: an integer value.
\item[flag] Specifies whether entries in $v$ are zero- or one-based.
Scope:{\bf global}.\\
Type:{\bf optional}.\\
Specified as: an integer value $0,1$, default $0$.
\end{description}

\begin{description}
\item[\bf On Return]
\item[desc\_a] the communication descriptor.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: a structured data of type \descdata.
\item[info] Error code.
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: an integer variable.\\
\end{description}

\section*{Notes}
\begin{enumerate}
\item On exit from this routine the descriptor is in the build state
\end{enumerate}


%
%%   psb_cdins %%
%
\subroutine{psb\_cdins}{Communication descriptor insert routine}

\syntax{call psb\_cdins}{nz, ia, ja, desc\_a, info}

\begin{description}
\item[\bf On Entry]
\item[nz] the number of points being inserted.\\
Scope: {\bf local}.\\
Type: {\bf required}.\\
Specified as: an integer value.
\item[ia] the row indices of the points being inserted.\\
Scope: {\bf local}.\\
Type: {\bf required}.\\
Specified as: an integer array of length $nz$.
\item[ja] the column indices of the points being inserted.\\
Scope: {\bf local}.\\
Type: {\bf required}.\\
Specified as: an integer array of length $nz$.
%% \item[is] the row offset.\\
%% Scope:{\bf local}.\\
%% Type:{\bf optional}.\\
%% Specified as: an integer value.
%% \item[js] the column offset.\\
%% Scope: {\bf local}.\\
%% Type: {\bf optional}.\\
%% Specified as: an integer value.
\end{description}

\begin{description}
\item[\bf On Return]
\item[desc\_a] the updated communication descriptor.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: a structured data of type \descdata.
\item[info] Error code.
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: an integer variable.
\end{description}
\section*{Notes}
\begin{enumerate}
\item This routine may only be called if the descriptor is in the
  build state
\end{enumerate}



%
%%   psb_cdasb %%
%
\subroutine{psb\_cdasb}{Communication descriptor assembly routine}

\syntax{call psb\_cdasb}{desc\_a, info}

\begin{description}
\item[\bf On Entry]
\item[desc\_a] the communication descriptor.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: a structured data of type \descdata.
\end{description}

\begin{description}
\item[\bf On Return]
\item[info] Error code.
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: an integer variable.
%\item[arg] 
\end{description}
\section*{Notes}
\begin{enumerate}
\item On exit from this routine the descriptor is in the assembled
  state. 
\end{enumerate}



%
%%   psb_cdcpy %%
%
\subroutine{psb\_cdcpy}{Copies a communication descriptor}

\syntax{call psb\_cdcpy}{desc\_out, desc\_a, info}

\begin{description}
\item[\bf On Entry]
\item[desc\_a] the communication descriptor.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: a structured data of type \descdata.

\end{description}

\begin{description}
\item[\bf On Return]
\item[desc\_out] the communication descriptor copy.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: a structured data of type \descdata.
\item[info] Error code.
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: an integer variable.\\
\end{description}


%
%%   psb_cdfree %%
%
\subroutine{psb\_cdfree}{Frees a communication descriptor}

\syntax{call psb\_cdfree}{desc\_a, info}

\begin{description}
\item[\bf On Entry]
\item[desc\_a] the communication descriptor to be freed.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: a structured data of type \descdata.
\end{description}

\begin{description}
\item[\bf On Return]
\item[info] Error code.
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: an integer variable.
\end{description}


%% %
%% %%   psb_cdren %%
%% %
%% \subroutine{psb\_cdren}{Applies a renumeration to a communication descriptor}

%% \syntax{call psb\_cdren}{trans, iperm, desc\_a, info}

%% \begin{description}
%% \item[\bf On Entry]
%% \item[trans] A character that specifies whether to permute $A$  or $A^T$.\\
%% Scope: {\bf local} \\
%% Type: {\bf required}\\
%% Specified as: a single character with value 'N' for $A$ or 'T' for $A^T$.\\
%% \item[iperm] An integer array containing permutation information.\\
%% Scope: {\bf local} \\
%% Type: {\bf required}\\
%% Specified as: an integer one-dimensional array.\\
%% \item[desc\_a] the communication descriptor.\\
%% Scope:{\bf local}.\\
%% Type:{\bf required}.\\
%% Specified as: a structured data of type \descdata.
%% \end{description}

%% \begin{description}
%% \item[\bf On Return]
%% \item[info] Error code.
%% Scope: {\bf local} \\
%% Type: {\bf required}\\
%% Specified as: an integer variable.
%% \end{description}




%
%%   psb_descprt %%
%
%% \subroutine{psb\_cdprt}{Prints a descriptor}

%% \syntax{call psb\_cdprt}{iout, desc\_a, glob, short}

%% \begin{description}
%% \item[\bf On Entry]
%% \item[iout] An integer that defines the output unit.
%% Scope: {\bf local} \\
%% Type: {\bf required}\\
%% Specified as: Integer scalar.\\
%% \item[desc\_a] The communication descriptor of type \descdata that
%%   must be printed.\\
%% Scope: {\bf local} \\
%% Type: {\bf required}\\
%% Specified as: a variable of type \descdata.\\
%% \end{description}

%% \begin{description}
%% \item[\bf On Return]
%% \item[glob] ??????
%% \item[short] ??????
%% \end{description}



%
%%   psb_spalloc %%
%
\subroutine{psb\_spall}{Allocates a sparse matrix}

\syntax{call psb\_spall}{a, desc\_a, info, nnz}

\begin{description}
\item[\bf On Entry]
\item[desc\_a] the communication descriptor.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: a structured data of type \descdata.
\item[nnz] An estimate of the number of nonzeroes in the local
  part of the assembled matrix.\\ 
Scope: {\bf global}.\\
Type: {\bf optional}.\\
Specified as: an integer value. 
\end{description}

\begin{description}
\item[\bf On Return]
\item[a] the matrix to be allocated.\\
Scope:{\bf local}\\
Type:{\bf required}\\
Specified as: a structured data of type \spdata.
\item[info] Error code.
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: an integer variable.
\end{description}
\section*{Notes}
\begin{enumerate}
\item On exit from this routine the sparse matrix  is in the build
  state.
\item The descriptor may be in either the build or assembled state.
\item Providing a good estimate for the number of nonzeroes $nnz$ in
  the assembled matrix may substantially improve performance in the
  matrix build phase, as it will reduce or eliminate the need for
  (potentially multiple) data reallocations. 
\end{enumerate}



%
%%   psb_spins %%
%
\subroutine{psb\_spins}{Insert a cloud of elements into a sparse matrix}

\syntax{call psb\_spins}{nz, ia, ja, val, a, desc\_a, info}

\begin{description}
\item[\bf On Entry]
\item[nz] the number of elements to be inserted.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: an integer scalar.
\item[ia] the row indices of the elements to be inserted.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: an integer array of size $nz$.
\item[ja] the column indices of the elements to be inserted.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: an integer array of size $nz$.
\item[val] the elements to be inserted.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: an array of size $nz$.
\item[desc\_a] The communication descriptor.\\
Scope: {\bf local}. \\
Type: {\bf required}.\\
Specified as: a variable of type \descdata.\\
%% \item[is] the starting row on matrix $a$.\\
%% Scope:{\bf local}.\\
%% Type:{\bf optional}.\\
%% Specified as: an integer vaule.
%% \item[js] the starting column on matrix $a$.\\
%% Scope:{\bf local}.\\
%% Type:{\bf optional}\\
%% Specified as: an integer value
\end{description}

\begin{description}
\item[\bf On Return]
\item[a] the matrix into which elements will be inserted.\\
Scope:{\bf local}\\
Type:{\bf required}\\
Specified as: a structured data of type \spdata.
\item[desc\_a] The communication descriptor.\\
Scope: {\bf local}. \\
Type: {\bf required}.\\
Specified as: a variable of type \descdata.\\
\item[info] Error code.\\
Scope: {\bf local} \\
Type: {\bf required}\\
\end{description}

\section*{Notes}
\begin{enumerate}
\item On entry to this routine the descriptor may be in either the
  build or assembled state.
\item On entry to this routine the sparse matrix may be in either the
  build or update state. 
\item If the descriptor is in the build state, then the sparse matrix
  ought also be in the build state; the action of the routine is to
  (implicitly) call \verb|psb_cdins| to add entries to the sparsity
  pattern;
\item If the descriptor is in the assembled state, then any entries in
  the sparse matrix that would generate additional communication
  requirements will be ignored; 
\item If the matrix is in the update state, any entries in positions
  that were not present in the original matrix will be ignored. 
\end{enumerate}

%
%%   psb_spasb %%
%
\subroutine{psb\_spasb}{Sparse matrix assembly routine}

\syntax{call psb\_spasb}{a, desc\_a, info, afmt, upd, dupl}

\begin{description}
\item[\bf On Entry]
\item[desc\_a] the communication descriptor.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: a structured data of type \descdata.
\item[afmt] the storage format for the sparse matrix.\\
Scope: {\bf global}.\\
Type: {\bf optional}.\\
Specified as: an array of characters. Defalt:  'CSR'.
\item[upd] Provide for updates to the matrix coefficients.\\
Scope: {\bf global}.\\
Type: {\bf optional}.\\
Specified as: integer, possible values: \verb|psb_upd_srch_|, \verb|psb_upd_perm_|
\item[dupl] How to handle duplicate coefficients.\\
Scope: {\bf global}.\\
Type: {\bf optional}.\\
Specified as: integer, possible values: \verb|psb_dupl_ovwrt_|,
\verb|psb_dupl_add_|, \verb|psb_dupl_err_|.
\end{description}

\begin{description}
\item[\bf On Return]
\item[a] the matrix to be assembled.\\
Scope:{\bf local}\\
Type:{\bf required}\\
Specified as: a structured data of type \spdata.
\item[info] Error code.
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: an integer variable.
\end{description}

\section*{Notes}
\begin{enumerate}
\item On entry to this routine the descriptor must  be in  the
  assembled state, i.e. \verb|psb_cdasb| must already have been called.
\item The sparse matrix may be in either the build or update state;
\item Duplicate entries are detected and handled in both build and
  update state, with the exception of the error action that is only
  taken in the build state, i.e. on the first assembly; 
\item If the update choice is \verb|psb_upd_perm_|, then subsequent
  calls to \verb|psb_spins| to update the matrix must be arranged in
  such a way as to produce exactly the same sequence of coefficient
  values as encountered at the first assembly; 
\item On exit from this routine the matrix is in the assembled state,
  and thus is suitable for the computational routines. 
\end{enumerate}



%% %
%% %%   psb_spcnv %%
%% %
%% \subroutine{psb\_spcnv}{Converts a sparse matrix storage format}

%% \syntax{call psb\_spcnv}{a, b, desc\_a, info}

%% \begin{description}
%% \item[\bf On Entry]
%% \item[a] the matrix to be converted.\\
%% Scope:{\bf local}\\
%% Type:{\bf required}\\
%% Specified as: a structured data of type \spdata.
%% \item[desc\_a] the communication descriptor.\\
%% Scope:{\bf local}.\\
%% Type:{\bf required}.\\
%% Specified as: a structured data of type \descdata.
%% \end{description}

%% \begin{description}
%% \item[\bf On Return]
%% \item[b] the converted matrix.\\
%% Scope:{\bf local}\\
%% Type:{\bf required}\\
%% Specified as: a structured data of type \spdata.
%% \item[info] Error code.
%% Scope: {\bf local} \\
%% Type: {\bf required}\\
%% Specified as: an integer variable.
%% \end{description}



%
%%   psb_spfree %%
%
\subroutine{psb\_spfree}{Frees a sparse matrix}

\syntax{call psb\_spfree}{a, desc\_a, info}

\begin{description}
\item[\bf On Entry]
\item[a] the matrix to be freed.\\
Scope:{\bf local}\\
Type:{\bf required}\\
Specified as: a structured data of type \spdata.
\item[desc\_a] the communication descriptor.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: a structured data of type \descdata.
\end{description}

\begin{description}
\item[\bf On Return]
\item[info] Error code.
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: an integer variable.
\end{description}




%
%%   psb_sprn %%
%
\subroutine{psb\_sprn}{Reinit sparse matrix structure for psblas routines.}

\syntax{call psb\_sprn}{a, decsc\_a, info, clear}

\begin{description}
\item[\bf On Entry]
\item[a] the matrix to be reinitialized.\\
Scope:{\bf local}\\
Type:{\bf required}\\
Specified as: a structured data of type \spdata.
\item[desc\_a] the communication descriptor.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: a structured data of type \descdata.
\item[clear] Choose whether to zero out matrix coefficients\\
Scope:{\bf local}.\\
Type:{\bf optional}.\\
Default: true.
\end{description}

\begin{description}
\item[\bf On Return]
\item[info] Error code.
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: an integer variable.
\end{description}
\section*{Notes}
\begin{enumerate}
\item On exit from this routine the sparse matrix is in the update
  state. 
\end{enumerate}
%
%%   psb_spupdate %%
%
%% \subroutine{psb\_spupdate}{Updates a sparse matrix.}

%% \syntax{call psb\_spupdate}{a, ia, ja, blck, desc\_a, info, ix, jx, updflag}

%% \begin{description}
%% \item[\bf On Entry]
%% \end{description}

%% \begin{description}
%% \item[\bf On Return]
%% \end{description}
%% %
%% %%   psb_csrp %%
%% %
%% \subroutine{psb\_csrp}{Applies a right permutation to a sparse matrix}

%% \syntax{call psb\_csrp}{trans, iperm, a, desc\_a, info}

%% \begin{description}
%% \item[\bf On Entry]
%% \item[trans] A character that specifies whether to permute $A$  or $A^T$.\\
%% Scope: {\bf local} \\
%% Type: {\bf required}\\
%% Specified as: a single character with value 'N' for $A$ or 'T' for $A^T$.\\
%% \item[iperm] An integer array containing permutation information.\\
%% Scope: {\bf local} \\
%% Type: {\bf required}\\
%% Specified as: an integer one-dimensional array.\\
%% \item[a] The sparse matrix to be permuted.\\
%% Scope: {\bf local} \\
%% Type: {\bf required}\\
%% Specified as: a \spdata variable.\\
%% \item[desc\_a] The communication descriptor of type \descdata.\\
%% Scope: {\bf local} \\
%% Type: {\bf required}\\
%% Specified as: a variable of type \descdata.\\
%% \end{description}

%% \begin{description}
%% \item[\bf On Return]
%% \item[info] Error code.\\
%% Scope: {\bf local} \\
%% Type: {\bf required}\\
%% Specified as: Integer scalar.\\
%% \end{description}


%
%%   psb_alloc %%
%
\subroutine{psb\_geall}{Allocates a dense matrix}

\syntax{call psb\_geall}{x, desc\_a, info, n}

\begin{description}
\item[\bf On Entry]
\item[desc\_a] The communication descriptor.\\
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: a variable of type \descdata.\\
\item[n] The number of columns of the dense matrix to be allocated.\\
Scope: {\bf local} \\
Type: {\bf optional}\\
Specified as: Integer scalar, default $1$. It is ignored if $x$ is a
rank-1 array. 
\end{description}

\begin{description}
\item[\bf On Return]
\item[x] The dense matrix to be allocated.\\
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: a rank one or two array with the ALLOCATABLE
attribute, of type real, complex or integer.\\
\item[info] Error code.
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: Integer scalar.
\end{description}


%
%%   psb_ins %%
%
\subroutine{psb\_geins}{Dense matrix insertion routine}

\syntax{call psb\_geins}{m, irw, val, x, desc\_a, info,dupl}

\begin{description}
\item[\bf On Entry]
\item[m] Number of rows in $val$  to be inserted.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: an integer value.
\item[irw] Indices of the rows to be inserted. Specifically, row $i$
  of $val$ will be inserted into the local row corresponding to the
  global row index $irw(i)$.
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: an integer array.
\item[val] the dense submatrix to be inserted.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: a rank 1 or 2  array.
Specified as: an integer value.
\item[desc\_a] the communication descriptor.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: a structured data of type \descdata.
\item[dupl] How to handle duplicate coefficients.\\
Scope: {\bf global}.\\
Type: {\bf optional}.\\
Specified as: integer, possible values: \verb|psb_dupl_ovwrt_|,
\verb|psb_dupl_add_|.
\end{description}

\begin{description}
\item[\bf On Return]
\item[x] the output dense matrix.\\
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: a rank one or two array with the ALLOCATABLE
attribute, of type real, complex or integer.\\
\item[info] Error code.
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: an integer variable.
\end{description}

\section*{Notes}
\begin{enumerate}
\item Dense vectors/matrices do not have an associated state;
\item Duplicate entries are either overwritten or added, there is no
  provision for raising an error condition. 
\end{enumerate}


%
%%   psb_asb %%
%
\subroutine{psb\_geasb}{Assembly a dense matrix}

\syntax{call psb\_geasb}{x, desc\_a, info}

\begin{description}
\item[\bf On Entry]
\item[desc\_a] The communication descriptor.\\
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: a variable of type \descdata.\\
\end{description}

\begin{description}
\item[\bf On Return]
\item[x] The dense matrix to be assembled.\\
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: a rank one or two array with the ALLOCATABLE
attribute, of type real, complex or integer.\\
\item[info] Error code.\\
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: Integer scalar.\\
\end{description}
%
%%   psb_free %%
%
\subroutine{psb\_gefree}{Frees a dense matrix}

\syntax{call psb\_gefree}{x, desc\_a, info}

\begin{description}
\item[\bf On Entry]
\item[x] The dense matrix to
  be freed.\\
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: a rank one or two array with the ALLOCATABLE
attribute, of type real, complex or integer.\\

\item[desc\_a] The communication descriptor.\\
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: a variable of type \descdata.\\
\end{description}

\begin{description}
\item[\bf On Return]
\item[info] Error code.\\
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: Integer scalar.\\
\end{description}


%
%%   psb_gelp %%
%
\subroutine{psb\_gelp}{Applies a left permutation to a dense matrix}

\syntax{call psb\_gelp}{trans, iperm, x, desc\_a, info}

\begin{description}
\item[\bf On Entry]
\item[trans] A character that specifies whether to permute $A$  or $A^T$.\\
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: a single character with value 'N' for $A$ or 'T' for $A^T$.\\
\item[iperm] An integer array containing permutation information.\\
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: an integer one-dimensional array.\\
\item[x] The dense matrix to be permuted.\\
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: a one or two dimensional array.\\
\item[desc\_a] The communication descriptor.\\
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: a variable of type \descdata.\\
\end{description}

\begin{description}
\item[\bf On Return]
\item[info] Error code.\\
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: Integer scalar.\\
\end{description}


%
%%   psb_glob_to_loc %%
%
\subroutine{psb\_glob\_to\_loc}{Global to local indices convertion}

\syntax{call psb\_glob\_to\_loc}{x, y, desc\_a, info, iact,owned}
\syntax*{call psb\_glob\_to\_loc}{x, desc\_a, info, iact,owned}

\begin{description}
\item[\bf On Entry]
\item[x] An integer vector of indices to be converted.\\
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: a rank one integer array.\\
\item[desc\_a] the communication descriptor.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: a structured data of type \descdata.
\item[iact] specifies action to be taken in case of range errors. 
Scope: {\bf global} \\
Type: {\bf optional}\\
Specified as: a character variable  \verb|I|gnore, \verb|W|arning or
\verb|A|bort, default \verb|I|gnore.
\item[owned] Specfies valid range of input 
Scope: {\bf global} \\
Type: {\bf optional}\\
If true, then only indices strictly owned by the current process are
considered valid, if false then halo indices are also
accepted. Default: false. 
\end{description}

\begin{description}
\item[\bf On Return]
\item[x] If $y$ is not present,
  then $x$ is overwritten with the translated integer indices. 
Scope: {\bf global} \\
Type: {\bf required}\\
Specified as: a rank one integer array.
\item[y] If $y$ is  present,
  then $y$ is overwritten with the translated integer indices, and $x$
  is left unchanged. 
Scope: {\bf global} \\
Type: {\bf optional}\\
Specified as: a rank one integer array.
\item[info] Error code.
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: an integer variable.
\end{description}

\section*{Notes}
\begin{enumerate}
\item If an input index is out of range, then the corresponding output
  index is set to a negative number;
\item The default \verb|I|gnore means that the negative output is the
  only action taken on an out-of-range input.
\end{enumerate}


%
%%   psb_loc_to_glob %%
%
\subroutine{psb\_loc\_to\_glob}{Local to global indices conversion}

\syntax{call psb\_loc\_to\_glob}{x, y, desc\_a, info, iact}
\syntax*{call psb\_loc\_to\_glob}{x, desc\_a, info, iact}

\begin{description}
\item[\bf On Entry]
\item[x] An integer vector of indices to be converted.\\
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: a rank one integer array.\\
\item[desc\_a] the communication descriptor.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: a structured data of type \descdata.
\item[iact] specifies action to be taken in case of range errors. 
Scope: {\bf global} \\
Type: {\bf optional}\\
Specified as: a character variable  \verb|E|, \verb|W| or \verb|A|. 
\end{description}

\begin{description}
\item[\bf On Return]
\item[x] If $y$ is not present,
  then $x$ is overwritten with the translated integer indices. 
Scope: {\bf global} \\
Type: {\bf required}\\
Specified as: a rank one integer array.
\item[y] If $y$ is not present,
  then $y$ is overwritten with the translated integer indices, and $x$
  is left unchanged. 
Scope: {\bf global} \\
Type: {\bf optional}\\
Specified as: a rank one integer array.
\item[info] Error code.
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: an integer variable.
\end{description}


\subroutine{psb\_geall}{Allocates a dense matrix}

\syntax{call psb\_geall}{x, desc\_a, info, n}

\begin{description}
\item[\bf On Entry]
\item[desc\_a] The communication descriptor.\\
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: a variable of type \descdata.\\
\item[n] The number of columns of the dense matrix to be allocated.\\
Scope: {\bf local} \\
Type: {\bf optional}\\
Specified as: Integer scalar, default $1$. It is ignored if $x$ is a
rank-1 array. 
\end{description}

\begin{description}
\item[\bf On Return]
\item[x] The dense matrix to be allocated.\\
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: a rank one or two array with the ALLOCATABLE
attribute, of type real, complex or integer.\\
\item[info] Error code.
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: Integer scalar.
\end{description}


%
%%   psb_ins %%
%
\subroutine{psb\_get\_boundary}{Extract list of boundary elements}

\syntax{call psb\_get\_boundary}{bndel, desc, info}

\begin{description}
\item[\bf On Entry]
\item[desc] the communication descriptor.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: a structured data of type \descdata.
\end{description}

\begin{description}
\item[\bf On Return]
\item[bndel] The list of boundary elements on the calling process, in
  local numbering.\\
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: a rank one array with the ALLOCATABLE
attribute, of type integer.\\
\item[info] Error code.
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: an integer variable.
\end{description}

\section*{Notes}
\begin{enumerate}
\item If there are no boundary elements (i.e., if the local part of
  the connectivity graph is self-contained) the output vector is set
  to \verb|NULL()|
\item Otherwise the size of \verb|bndel| will be exactly equal to the
  number of boundary elements. 
\end{enumerate}

\subroutine{psb\_get\_overlap}{Extract list of overlap elements}

\syntax{call psb\_get\_overlap}{ovrel, desc, info}

\begin{description}
\item[\bf On Entry]
\item[desc] the communication descriptor.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: a structured data of type \descdata.
\end{description}

\begin{description}
\item[\bf On Return]
\item[ovrel] The list of overlap elements on the calling process, in
  local numbering.\\
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: a rank one array with the ALLOCATABLE
attribute, of type integer.\\
\item[info] Error code.
Scope: {\bf local} \\
Type: {\bf required}\\
Specified as: an integer variable.
\end{description}

\section*{Notes}
\begin{enumerate}
\item If there are no overlap elements the output vector is set
  to \verb|NULL()|
\item Otherwise the size of \verb|ovrel| will be exactly equal to the
  number of overlap elements. 
\end{enumerate}


\subroutine{psb\_cd\_get\_local\_rows}{Get number of local rows}

\syntax{nr = psb\_cd\_get\_local\_rows}{desc}

\begin{description}
\item[\bf On Entry]
\item[desc] the communication descriptor.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: a structured data of type \descdata.
\end{description}

\begin{description}
\item[\bf On Return]
\item[Function value] The number of local rows, i.e. the number of
  rows owned by the current process; as explained in~\ref{sec:intro},
  it is equal to $|{\cal I}_i| + |{\cal B}_i|$. The returned value is
  specific to the calling process. 
\end{description}


\subroutine{psb\_cd\_get\_local\_cols}{Get number of local cols}

\syntax{nc = psb\_cd\_get\_local\_cols}{desc}

\begin{description}
\item[\bf On Entry]
\item[desc] the communication descriptor.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: a structured data of type \descdata.
\end{description}

\begin{description}
\item[\bf On Return]
\item[Function value] The number of local cols, i.e. the number of
  indices used by the current process, including both local and halo
  indices; as explained in~\ref{sec:intro}, 
  it is equal to  $|{\cal I}_i| + |{\cal B}_i| +|{\cal H}_i|$. The
  returned value is specific to the calling process. 
\end{description}


\subroutine{psb\_cd\_get\_global\_rows}{Get number of global rows}

\syntax{nr = psb\_cd\_get\_global\_rows}{desc}

\begin{description}
\item[\bf On Entry]
\item[desc] the communication descriptor.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: a structured data of type \descdata.
\end{description}

\begin{description}
\item[\bf On Return]
\item[Function value] The number of global rows in the mesh
\end{description}


\subroutine{psb\_cd\_get\_contex}{Get communication context}
\syntax{ictxt = psb\_cd\_get\_context}{desc}

\begin{description}
\item[\bf On Entry]
\item[desc] the communication descriptor.\\
Scope:{\bf local}.\\
Type:{\bf required}.\\
Specified as: a structured data of type \descdata.
\end{description}

\begin{description}
\item[\bf On Return]
\item[Function value] The communication context.
\end{description}



\subroutine{psb\_sp\_get\_nrows}{Get number of  rows in a sparse matrix}

\syntax{nr = psb\_sp\_get\_nrows}{a}

\begin{description}
\item[\bf On Entry]
\item[a] the sparse matrix\\
Scope:{\bf local}\\
Type:{\bf required}\\
Specified as: a structured data of type \spdata.
\end{description}

\begin{description}
\item[\bf On Return]
\item[Function value] The number of  rows  of sparse matrix \verb|a|.
\end{description}


\subroutine{psb\_sp\_get\_ncols}{Get number of  columns in a sparse matrix}

\syntax{nr = psb\_sp\_get\_ncols}{a}

\begin{description}
\item[\bf On Entry]
\item[a] the sparse matrix\\
Scope:{\bf local}\\
Type:{\bf required}\\
Specified as: a structured data of type \spdata.
\end{description}

\begin{description}
\item[\bf On Return]
\item[Function value] The number of  columns  of sparse matrix \verb|a|.
\end{description}


\subroutine{psb\_sp\_get\_nnzeros}{Get number of nonzero elements in a sparse matrix}

\syntax{nr = psb\_sp\_get\_nnzeros}{a}

\begin{description}
\item[\bf On Entry]
\item[a] the sparse matrix\\
Scope:{\bf local}\\
Type:{\bf required}\\
Specified as: a structured data of type \spdata.
\end{description}

\begin{description}
\item[\bf On Return]
\item[Function value] The number of nonzero elements stored in sparse matrix \verb|a|.
\end{description}

\section*{Notes}
\begin{enumerate}
\item The function value is specific to the storage format of matrix
  \verb|a|; some storage formats employ padding, thus the returned
  value for the same matrix may be different for different storage choices.
\end{enumerate}


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