The end operator must be used within an array index expression.

Can anybody please help me to plot minf which is defined at the end. Below is my code

clear all; close all; clc;

    Vrest = 0; % mV− change this to −65 ifdesired
    dt = 0.01; % ms
    totalTime = 200; % ms 

    C = 20; % uF/cm^2

    V_Ca = 120; %mV %Reversal potential for Ca2+ current
    V_K = -84;  %mV %Reversal potential for K+ current
    V_Leak = -60;  %mV %Reversal potential for leak current

    g_Ca = 4.4; % mS/cm^2 % Maximal conductance associated with Ca2+ current
    g_K = 8;    % mS/cm^2 % Maximal conductance associated with K+ current
    g_Leak = 2; % mS/cm^2 % Conductance associated with leak current


    % Vector oftimesteps 
    t = [0:dt:totalTime];
    % samples = length(t);
    V = zeros(size(t));

    % Current input −− change this to see how different inputs affect the neuron 
    I_current = ones(1,length(t))*0.0; 
    I_current(10/dt:end) = 60;  % Input of 0 microA/cm2 beginning at 50 ms and steady until end of time period.
    
    
    % initializing values 
    V(1) = Vrest; % membrane potential is starting at its resting state

    % separate functions to get the alpha and beta values
    [alphaW, betaW] = w_equations(V(1)); 

    % initializing gating variables to the asymptotic values when membrane potential 
    % is set to the membrane resting value based on equation 13 
    w(1) = (alphaW / (alphaW + betaW)); 
    
    % repeat for time determined in totalTime , by each dt 
    for i = 1:length(t)
        % calculate new alpha and beta based on last known membrane potenatial 
        [alphaW, betaW] = w_equations(V(i));

    % conductance variables − computed separately to show how this 
    % changes with membrane potential in one ofthe graphs 
    conductance_Ca(i) = g_Ca*(m_inf(i));
    conductance_K(i)=g_K*(w(i));
    % retrieving ionic currents 
    I_Ca(i) = conductance_Ca(i)*(V(i)-V_Ca);
    I_K(i) = conductance_K(i)*(V(i)-V_K);
    I_Leak(i) = g_Leak*(V(i)-V_Leak);

    % Calculating the input
    Input = I_current(i) - (I_Ca(i) + I_K(i) + I_Leak(i));
    % Calculating the new membrane potential 
    V(i+1) = V(i) + Input* dt*(1/C);
    % getting new values for the gating variables  
    w(i+1) = w(i) + (alphaW *(1-w(i)) - betaW * w(i))*dt;
    end

figure('Name', 'Gating Parameters')
plot(t(45/dt:end),minf(45/dt:end-1), 'r',t(45/dt:end), w(45/dt:end-1), 'g', 'LineWidth', 2)
legend('minf', 'w') 
xlabel('Time (ms)') 
ylabel('')
title('Gating Parameters')


figure('Name', 'Membrane Potential vs input')
subplot(2,1,1)
plot(t(10/dt:end),V(10/dt:end-1), 'LineWidth', 2)
xlabel('Time (ms)')
ylabel('Voltage (mV)')
title('Action Potential')
subplot(2,1,2) 
plot(t(10/dt:end),I_current(10/dt:end), 'r', 'LineWidth', 2) 
xlabel('Time (ms)')
ylabel('Voltage (mV)')
title('Input')

figure('Name', 'Conductance') 
plot(t(10/dt:end),V(10/dt:end-1), 'r', t(10/dt:end), conductance_Ca(10/dt:end), 'b', t(10/dt:end), conductance_K(10/dt:end), 'g', 'LineWidth', 2)
legend('Action Potential', 'Ca+ Conductance', 'K+ Conductance')
xlabel('Time (ms)') 
ylabel('Voltage (mV)')
title('Conduction of K+ and Ca+')

figure('Name', 'Currents') 
plot(t(10/dt:end),I_Ca(10/dt:end), 'r',t(10/dt:end),I_K(10/dt:end), 'b', 'LineWidth', 2) 
xlabel('Time (ms)')
ylabel('Current')
title('Currents')


% Special graph to show ionic current movement 
Vrest = -12; 
voltage = [-100:0.01:100]; 
for i = 1:length(voltage)
    [alphaW, betaW] = w_equations(voltage(i)); 

    tauw(i) = 1/(alphaW+betaW); 

    xw(i) = alphaW/(alphaW+betaW); 
  
aW(i) = alphaW; 
bW(i) = betaW;
end
figure('Name', 'Equilibrium Function'); 
plot(voltage, xw,'LineWidth', 2); 
legend('w'); 
title('Equilibrium Function');
xlabel('mV')
ylabel('x(u)');
xlabel('Time (ms)')

%%%%%%%% functions section - always after main code %%%%%%%%%%%%%%%
 %calculate alpha w and beta w
function [alpha_w, beta_w] = w_equations(V)
V_1  = -1.2; % mV
V_2 = 18; % mV
V_3 = 2; % mV
V_4 = 30; % mV
phi = 0.04; %1/ms %Rate scaling parameter
alpha_w = 1/2*phi* cosh((V-V_3)/(2*V_4))*(1 + tanh((V-V_3)/V_4));
beta_w = 1/2*phi* cosh((V-V_3)/(2*V_4))*(1 - tanh((V-V_3)/V_4));
end 
%%%%%%%% functions section - always after main code %%%%%%%%%%%%%%%
function [minf] = m_inf(V)
V_1  = -1.2; % mV
V_2 = 18; % mV
V_3 = 2; % mV
V_4 = 30; % mV
minf = 1/2*(1 + tanh((V-V_1)/V_2));
end

Answer 1

[Geoff Hayes]

@Haya Ali - from this line

plot(t(45/dt:end),minf(45/dt:end-1), 'r',t(45/dt:end), w(45/dt:end-1), 'g', 'LineWidth', 2)

what is minf? I do not see that it is has been defined prior to this line of code. From context, the assumption is that it is an array...