% GHodgkin_Huxley
% Carol Lucas
% Simulates the Hodgkin_Huxley Model.  Can be used to get figures like 2.13

global VNa VK VL gNa gK gL C Iapp Vinit minit hinit ninit tend

clear t;

R=input('Hit any number to erase figures: ');
if length(R)~=0; 
	figure(1);clf;figure(2);clf;figure(3);clf;
	end

tstart=0;

k=1;t=[tstart:.25:tend];

xint=[Vinit;minit;hinit;ninit];

[t,x]=ode45('Ghhfun',t,xint);

figure(1);plot(t,x(:,1));axis([0 tend -80 60]);
xlabel('time (ms)'),ylabel('voltage (mv)');hold on;
figure(2);subplot(221);plot(t,x(:,2));
xlabel('time (ms)'),ylabel('m');hold on;
subplot(222);plot(t,x(:,3))
xlabel('time (ms)'),ylabel('h');hold on;
subplot(223);plot(t,x(:,4));
xlabel('time (ms)'),ylabel('n');hold on;


clear VRay taum minf tauh hinf taun ninf;
VRay=[-75:.50001:75];

for k = 1:length(VRay);
	 V=VRay(k);
     taum(k)=1/(0.1*(V+40)/(1-exp(-(V+40)/10))+4*exp(-(V+65)/18));
     minf(k)=(0.1*(V+40)/(1-exp(-(V+40)/10)))*taum(k);
     tauh(k)=1/(0.07*exp(-(V+65)/20)+(1/(1+exp(-(V+35)/10))));
     hinf(k)=0.07*exp(-(V+65)/20)*tauh(k);
     taun(k)=1/(0.01*(V+55)/(1-exp(-(V+55)/10))+0.125*exp(-(V+65)/80));
     ninf(k)=(0.01*(V+55)/(1-exp(-(V+55)/10)))*taun(k);
end


figure(3);subplot(211);plot(VRay,taum,VRay,tauh,VRay,taun);
title('TAUS FOR m, h and n'),xlabel('voltage (mv)');hold on;
subplot(212);plot(VRay,minf,VRay,hinf,VRay,ninf);
title('INFS FOR m, h and n'),xlabel('voltage (mv)');hold on;
figure(1);