% -*- texinfo -*-
%
% @deftypefn {Function File} @
% {@var{A}} = BIM1Aadvdiff (@var{mesh}, @var{alpha}, @var{gamma}, @var{eta}, @var{beta})
%
% Builds the Scharfetter-Gummel matrix for the
% discretization of the LHS
% of the equation
% @iftex
% @tex
% $ - ( \alpha \gamma ( \eta u' - \vect{beta} u ))' = f $
% @end tex
% @end iftex
% @ifnottex
% - (@var{alpha} * @var{gamma} (@var{eta} u' - @var{beta} u ))' = f
% @end ifnottex
%
% where:
% @itemize @minus
% @item @var{alpha}: element-wise constant scalar function
% @item @var{eta}, @var{gamma}: piecewise linear conforming
% scalar functions
% @item @var{beta}: element-wise constant vector function
% @end itemize
%
% Instead of passing the vector field @var{beta} directly
% one can pass a piecewise linear conforming scalar function
% @var{phi} as the last input. In such case @var{beta} = grad @var{phi}
% is assumed. If @var{phi} is a single scalar value @var{beta}
% is assumed to be 0 in the whole domain.
%
%
% @seealso{BIM1Arhs, BIM21reaction, BIM1Alaplacian}
% @end deftypefn