% -*- texinfo -*-
% @deftypefn {Function File} {[@var{b}, @var{c}] =} spdiags (@var{a})
% @deftypefnx {Function File} {@var{b} =} spdiags (@var{a}, @var{c})
% @deftypefnx {Function File} {@var{b} =} spdiags (@var{v}, @var{c}, @var{a})
% @deftypefnx {Function File} {@var{b} =} spdiags (@var{v}, @var{c}, @var{m}, @var{n})
% A generalization of the function @code{diag}. Called with a single
% input argument, the non-zero diagonals @var{c} of @var{A} are extracted.
% With two arguments the diagonals to extract are given by the vector
% @var{c}.
%
% The other two forms of @code{spdiags} modify the input matrix by
% replacing the diagonals. They use the columns of @var{v} to replace
% the columns represented by the vector @var{c}. If the sparse matrix
% @var{a} is defined then the diagonals of this matrix are replaced.
% Otherwise a matrix of @var{m} by @var{n} is created with the
% diagonals given by @var{v}.
%
% Negative values of @var{c} represent diagonals below the main
% diagonal, and positive values of @var{c} diagonals above the main
% diagonal.
%
% For example
%
% @example
% @group
% spdiags (reshape (1:12, 4, 3), [-1 0 1], 5, 4)
% @result{} 5 10 0 0
% 1 6 11 0
% 0 2 7 12
% 0 0 3 8
% 0 0 0 4
% @end group
% @end example
%
% @end deftypefn