% -*- texinfo -*-
% @deftypefn {Function File} {[@var{jx},@var{jy}]} = BIM2Cglobalflux(@var{mesh},@var{u},@var{alpha},@var{gamma},@var{eta},@var{beta})
%
% Builds the Scharfetter-Gummel approximation of the vector field
% @iftex
% @tex
% $ \vect{J}(u) = \alpha \gamma (\eta\vect{\nabla}u-\vect{beta}u) $
% @end tex
% @end iftex
% @ifnottex
% J(@var{u}) = @var{alpha}* @var{gamma} * (@var{eta} * grad @var{u} - @var{beta} * @var{u}))
% @end ifnottex
%
% where:
% @itemize @minus
% @item @var{alpha}: element-wise constant scalar function
% @item @var{eta}, @var{u}, @var{gamma}: piecewise linear conforming scalar functions
% @item @var{beta}: element-wise constant vector function
% @end itemize
%
% J(@var{u}) is an element-wise constant vector function
%
% 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{BIM2Cpdegrad,BIM2Aadvdiff}
% @end deftypefn