function mob = Ufielddepmob(imesh,u0,F,vsat,b)


% mob = Ufielddepmob(imesh,u0,F,vsat,b) 
% Computes field dependent mobility

% This file is part of 
%
%            SECS2D - A 2-D Drift--Diffusion Semiconductor Device Simulator
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%            Copyright (C) 2004-2006  Carlo de Falco
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%  SECS2D is free software; you can redistribute it and/or modify
%  it under the terms of the GNU General Public License as published by
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[Ex,Ey]=Updegrad(imesh,F);


ef = sqrt(Ex.^2+Ey.^2);

if Ucolumns(ef)>Urows(ef)
    ef=ef';
end
if Ucolumns(u0)>Urows(u0)
    u0=u0';
end

mob = u0 ./ (1+(u0 .* ef ./ vsat).^b).^(1/b);

