%% ODE for figure 5.19 Chay-Kaizer 0r Morrris Lecar Pancreatic Beta Cell
%%  Carol Lucas

function xdot=mlbetafun(t,x,flag,vlpm)
% Morris-Lecar beta-cell like model
v=x(1,1);
n=x(2,1);
c=x(3,1);
%
vk=-75; vl=-75; vca=25;
i=0; gk=2700; gl=150; gca=1000; cm=5300;
v1=-20.0; v2=24; v3=-16; v4=11.2; phi=0.035;
gkca=2000.0; Kca=5.0;


minf=.5*(1+tanh((v-v1)/v2));
ninf=.5*(1+tanh((v-v3)/v4));
tau=1/(cosh((v-v3)/(2*v4)));
%
% Calcium Handling
 alpha=4.50e-6; f=0.001;

% Ikca
ikca =gkca/(1+(Kca/c))*(v-vk);

ica = gca*minf*(v-vca);

% equations
xdot(1,1)=(-i+gl*(vl-v)+gk*n*(vk-v)- ica - ikca)/cm;
xdot(2,1)=phi*(ninf-n)/tau;
xdot(3,1)=f*(-alpha*ica - vlpm*c);