% 
% Backward Euler on a Passive Sphere
%
%  usage   beps(dt,Tfin)
%
%  e.g.    beps(0.01,40)
%

function beps(dt,Tfin)


VCl = -68;	% mV
A = 4*pi*1e-6;	% cm^2 patch area
Cm = 1;         % micro F/cm^2
gCl = 0.3;      % mS/cm^2
tau = Cm/gCl;   % ms

j = 1;
v(1) = VCl;
t(1) = 0;

while t < Tfin

   t(j+1) = j*dt;

   Istim = (t(j+1)>2)*(t(j+1)<22)*1e-5;    % 10 pA 20 ms pulse

   v(j+1) = (v(j) + dt*(VCl/tau + Istim/A/Cm))/(1+dt/tau);

   j = j + 1;

end

plot(t,v)
xlabel('t  (ms)','fontsize',16)
ylabel('V  (mV)','fontsize',16)