function B = prtv(A,i,j)

% PRTV  Retrieve elements of matrices in long format.
% 	B = PRTV(A,i,j) retrieves the polynomials corresponding to
%	the (i,j) elements of an m-by-n matrix of polynomials stored 
%	in an (m*n + 2)-by-(k+1) matrix (long format). 
%	k is the highest degree of the polynomials in A. If length(i) 
%	is M, LENGTH(j) is N, then B will be an (M*N + 2)-by-(k+1) 
%	matrix of polynomials in long format.
%	B = PRTV(A,V) retrieves the polynomials corresponding to the
%	elements in V. The resulting matrix of polynomials is the
%	same size as V.
%
%	To specify all the elements along one dimension use ':'.
%	For instance, PRTV(A,2:3,':') retrieves all the elements
%	in the second and third rows of A.
%
%	See also ETCHG, ELCHG

%	Written by Serge Tchikanda 06/13/96.
%       Last revised by Serge Tchikanda 06/17/96.


[m,n] = psize(A);
[m1,n1]=size(A);
D = A(2,1);
if isempty(m) | isempty(n)
   return
end

if nargin == 2
   if isempty(i)
      return
   end
   if strcmp(':',i)
      i = [1:m*n]'; 
   end
   [mi,ni]=size(i);
   [B,d] = gpet(A,i);
   [mb,nb]=size(B);
   B = [[mi;d] zeros(2,nb-1);B];
else
   if isempty(i) | isempty(j);
      return
   end
   if strcmp(':',i)
      i = 1:m; 
   end
   if  strcmp(':',j)
      j = 1:n; 
   end
   [B,d] = gpel(A,i,j);
   li = length(i);
   [mb,nb]=size(B);
   B = [[li;d] zeros(2,nb-1);B];
end