Keep getting error message Index exceeds the number of array elements (1) line 77

dt=50*10^-3; %50 microsencods deltatime

stimAmplitude=200;

stimDuration=150;

%Nerst Potential

EK=-72.100;

ENa=52.400;

EL=-49.187;

%Membrane conductivity

gKbar=36.0;

gNabar=120;

gL=0.3;

gK=0.367;

gNa=0.011;

%Gating Probability n,m,h

n=0.41768;

m=0.05293;

h=0.59612;

%Membrane capacitance

Cm=1.00;

%Temper

Temp=6.30;

%Transmembrane Potential

Vm=-60.000;

%Resting Potentail

Vr=-60.000;

%Stimulus Current

Is=0;

%Total membrane current for patch if no stimulus

Im=0;

vm=[];

%Calculations of alpha and Betas for h,n and m

% % a_h=0.07.*exp(-vm./20)

% % b_h=1./((exp((30-vm)/10)+1))

% % a_m=0.1.*((25-vm)./(exp((0.1.*(25-vm)))-1))

% % b_m=4.*exp(-vm/18)

% % a_n=((0.01.*(10-vm))./((exp((10-vm)./10))-1))

% % b_n=0.125.*exp(-vm./80)

%

% %dn

% dn=(a_n.*(1-n))-(b_n.*n)

% dm=(a_m.*(1-m))-(b_m.*m)

% dh=(a_h.*(1-h))-(b_h.*h)

% change in variables

for i = 1:8

vm(i) = Vm(i) - Vr;

Am(i) = ((0.1*(25-vm(i)))/(exp(0.1*(25-vm(i)))-1))*1000; %Alpha & beta for M

Bm(i) = (4*exp(-vm(i)/18))*1000;

dm(i) = (Am(i)*(1-m(i))-Bm(i)*m(i))*dt; % change in M

m(i+1) = m(i)+dm(i); % inital M + change in M

Ah(i) = (0.07*exp(-vm(i)/20))*1000; % H

Bh(i) = (1/(exp((30-vm(i))/10)+1))*1000;

dh(i) = (Ah(i)*(1-h(i))-Bh(i)*h(i))*dt;

h(i+1)= h(i)+dh(i);

An(i) = (0.01*(10-vm(i))/(exp((10-vm(i))/10)-1))*1000; % N

Bn(i) = (0.125*exp(-vm(i)/80))*1000;

dn(i) = (An(i)*(1-n(i))-Bn(i)*n(i))*dt;

n(i+1) = n(i)+dn(i);

gK(i) = gKbar*n(i)^4; % Change in conductance for K & Na

gNa(i) = gNabar*m(i)^3.*h(i);

Ik(i) = gK(i)*(Vm(i)-EK); % Change in current

Ina(i) = gNa(i)*(Vm(i)-ENa);

Il(i) = gL*(Vm(i)-EL);

% Membrane current

dv(i) = dt/Cm*Im(i); % change in voltage

Vm(i+1) = Vm(i) + dv(i)*1000; % membrane voltage

end

[Mohammad Sami]

You defined Im = 0 and then you are trying to use it on line 77 with Im(i). As the for loop increments to 2, it will try to access Im(2), which does not exist.