    function
       petsc-3.7.1 2016-05-15
       Report Typos and Errors [varargout] = PetscBinaryRead(inarg,varargin)
    %
    %   [varargout] = PetscBinaryRead(inarg,['complex',false or true],['indices','int32' or 'int64'],['cell',cnt],['precision','float64' or 'float32'])
    %
    %  Reads in PETSc binary file matrices or vectors
    %  emits as Matlab sparse matrice or vectors.
    %
    %  [] indices optional arguments
    %  There are no [] in the arguments
    %
    %  Examples: A = PetscBinaryRead('myfile'); read from file
    %            b = PetscBinaryRead(1024);   read from socket
    %            c = PetscBinaryRead();       read from default socket PETSc uses
    %
    %  Argument may be file name (string), socket number (integer)
    %  or any Matlab class that provides the read() and close() methods
    %  [We provide PetscOpenFile() and PetscOpenSocket() for binary files and sockets]
    %  For example: fd = PetscOpenFile('filename');
    %                a = PetscBinaryRead(fd);
    %                b = PetscBinaryRead(fd);
    %
    %  'complex', true indicates the numbers in the file are complex, that is PETSc was built with --with-scalar-type=complex
    %  'indices','int64' indicates the PETSc program was built with --with-64-bit-indices
    %  'cell',cnt  means return a Matlab cell array containing the first cnt objects in the file, use 10,000 to read in all objects
    %  'precision','float32' indicates the PETSc program was built with --with-precision=single
    %
    %  Examples:  A = PetscBinaryRead('myfile','cell',10000);  read all objects in file
    %             A = PetscBinaryRead(1024,'cell',2);  read two objects from socket
    %
    if nargin == 0
      fd = PetscOpenSocket();
    else if ischar(inarg)
      fd = PetscOpenFile(inarg);
    else if isnumeric(inarg)
      fd = PetscOpenSocket(inarg);
    else % assume it is a PetscOpenFile or PetscOpenSocket object and handles read()
      fd = inarg;
    end
    end
    end

    indices = 'int32';
    precision = 'float64';
    arecell = 0;
    arecomplex = false;

    tnargin = nargin;
    for l=1:nargin-2
      if ischar(varargin{l}) && strcmpi(varargin{l},'indices')
        tnargin = min(l,tnargin-1);
        indices = varargin{l+1};
      end
      if ischar(varargin{l}) && strcmpi(varargin{l},'precision')
        tnargin = min(l,tnargin-1);
        precision = varargin{l+1};
      end
      if ischar(varargin{l}) && strcmpi(varargin{l},'cell')
        tnargin = min(l,tnargin-1);
        arecell = varargin{l+1};
      end
      if ischar(varargin{l}) && strcmpi(varargin{l},'complex')
        tnargin = min(l,tnargin-1);
        arecomplex = varargin{l+1};
      end
    end

    if strcmp(precision,'float128')
      precision = 'float64';
      system(['./convert -f ' inarg]);
      fd = PetscOpenFile([inarg '_double']);
    end

    if arecell
      narg = arecell;
      rsult = cell(1);
    else
      narg = nargout;
    end

    for l=1:narg
      header = double(read(fd,1,indices));
      if isempty(header)
        if arecell
          varargout(1) = {result};
          return
        else
          disp('File/Socket does not have that many items')
        end
        return
      end
      if header == 1211216 % Petsc Mat Object

        header = double(read(fd,3,indices));
        m      = header(1);
        n      = header(2);
        nz     = header(3);
        if (nz == -1)
          if arecomplex
            s     = read(fd,2*m*n,precision);
            iReal = 1:2:n*m*2-1;
            iImag = iReal +1 ;
            A     = complex(reshape(s(iReal),n,m)',reshape(s(iImag),n,m)') ;
          else
            s   = read(fd,m*n,precision);
            A   = reshape(s,n,m)';
          end
        else
          nnz = double(read(fd,m,indices));  %nonzeros per row
          sum_nz = sum(nnz);
          if(sum_nz ~=nz)
            str = sprintf('No-Nonzeros sum-rowlengths do not match %d %d',nz,sum_nz);
            error(str);
          end
          j   = double(read(fd,nz,indices)) + 1;
          if arecomplex
            s   = read(fd,2*nz,precision);
          else
            s   = read(fd,nz,precision);
          end
          i   = ones(nz,1);
          cnt = 1;
          for k=1:m
            next = cnt+nnz(k)-1;
            i(cnt:next,1) = (double(k))*ones(nnz(k),1);
            cnt = next+1;
          end
          if arecomplex
            A = sparse(i,j,complex(s(1:2:2*nz),s(2:2:2*nz)),m,n,nz);
          else
            A = sparse(i,j,s,m,n,nz);
          end
        end
        if arecell
          result{l} = A;
        else
          varargout(l) = {A};
        end
      elseif  header == 1211214 % Petsc Vec Object
        m = double(read(fd,1,indices));
        if arecomplex
          v = read(fd,2*m,precision);
          v = complex(v(1:2:2*m),v(2:2:2*m));
        else
          v = read(fd,m,precision);
        end
        if arecell
          result{l} = v;
        else
          varargout(l) = {v};
        end

      elseif  header == 1211218 % Petsc IS Object
        m = double(read(fd,1,indices));
        v = read(fd,m,'int') + 1; % Indexing in Matlab starts at 1, 0 in PETSc
        if arecell
          result{l} = v;
        else
          varargout(l) = {v};
        end

      elseif header == 1211219 % Petsc Bag Object
        b = PetscBagRead(fd);
        if arecell
          result{l} = b;
        else
          varargout(l) = {b};
        end

      elseif header == 1211221 % Petsc DM Object
        m  = double(read(fd,7,indices));
        me = double(read(fd,5,indices));
        b = [' dm ' int2str(m(3)) ' by ' int2str(m(4)) ' by ' int2str(m(5))];
        if arecell
          result{l} = b;
        else
          varargout(l) = {b};
        end

      else
        disp(['Found unrecogonized header ' int2str(header) ' in file. If your file contains complex numbers'])
        disp(' then call PetscBinaryRead() with "complex",true as two additional arguments')
        return
      end

    end

    if arecell
      varargout(1) = {result};
    end

    % close the reader if we opened it

    if nargin > 0
      if (ischar(inarg) || isinteger(inarg)) close(fd); end;
    end