function ndot=vcfun(t,no,flag,Vbase,Vo,So,A)
%  This only changes to V from 10 to 50 ms
V=-60;
if t>10 & t<50;
	V=Vbase;
	end;
ninf=.5*(1+tanh((V-Vo)/(2*So)));
tau=A/cosh((V-Vo)/(2*So));
ndot=-(no-ninf)/tau;