Unrecognized function or variable 'm_equations'

Please help me to resolve the following error.

Error in untitled (line 38)
    [alphaM, betaM] = m_equations(V(1), Vrest)

The code is

    clear all; close all; clc;


    Vrest = 0; % mV− change this to −65 ifdesired
    dt = 0.01; % ms
    totalTime = 150; % ms 

    C = 20; % uF/cm^2
    V_1  = -1.2; % mV
    V_2 = 18; % mV
    V_3 = 2; % mV
    V_4 = 30; % mV

    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
     
    phi = 0.04; %1/ms %Rate scaling parameter

    % 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(50/dt:end) = 90;  % Input of 90 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
    [alphaM, betaM] = m_equations(V(1), Vrest); 
    [alphaW, betaW] = w_equations(V(1), Vrest); 

    % initializing gating variables to the asymptotic values when membrane potential 
    % is set to the membrane resting value based on equation 13 
    m(1) = (alphaM / (alphaM + betaM)); 
    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 
        [alphaM, betaM] = m_equations(V(i), Vrest); 
        [alphaW, betaW] = w_equations(V(i), Vrest);

    % conductance variables − computed separately to show how this 
    % changes with membrane potential in one ofthe graphs 
    conductance_Ca(i) = g_Ca*(m(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 
    m(i+1) = m(i) + (alphaM *(1-m(i)) - betaM * m(i))*dt; 
    w(i+1) = w(i) + (alphaN *(1-w(i)) - betaN * w(i))*dt;
    end
figure('Name', 'Gating Parameters')
plot(t(45/dt:end),m(45/dt:end-1), 'r',t(45/dt:end), w(45/dt:end-1), 'b', 'LineWidth', 2)
legend('m', 'W') 
xlabel('Time (ms)') 
ylabel('')
title('Gating Parameters')
figure('Name', 'Membrane Potential vs input')
subplot(2,1,1)
plot(t(45/dt:end),V(45/dt:end-1), 'LineWidth', 2)
xlabel('Time (ms)')
ylabel('Voltage (mV)')
title('Action Potential')
xlabel('Time (ms)')

% Special graph to show ionic current movement 
Vrest = 0; 
voltage = [-100:0.01:100]; 
for i = 1:length(voltage)
    [alphaM, betaM] = m_equations(voltage(i), Vrest);
    [alphaW, betaW] = w_equations(voltage(i), Vrest); 

    taum(i) = 1/(alphaM+betaM);
    tauw(i) = 1/(alphaW+betaW); 
   
    xm(i) = alphaM/(alphaM+betaM);
    xw(i) = alphaw/(alphaw+betaw); 
  

aM(i) = alphaM; 
bM(i) = betaM;

aM(i) = alphaM; 
bW(i) = betaW;
end
figure('Name', 'Equilibrium Function'); 
plot(voltage, xm, voltage, xw,'LineWidth', 2); 
legend('m', 'w'); 
title('Equilibrium Function');
xlabel('mV');
ylabel('x(u)');
xlabel('Time (ms)')

function MorrisLecar
%%%%%%%% functions section - always after main code %%%%%%%%%%%%%%%
% calculate alpha m and beta m
function [alpha_m, beta_m] = m_equations(phi,V,V_1,V_2,V_3,V_4)
alpha_m = 0.5*phi* cosh((V-V3)/(2*V4))*(1 + tanh((V-V1)/V2));
beta_m = 0.5*phi* cosh((V-V3)/(2*V4))*(1 - tanh((V-V1)/V2));
end 
% calculate alpha w and beta w
function [alpha_w, beta_w] = w_equations(phi,V,V_3,V_4)
alpha_m = 0.5*phi* cosh((V-V3)/(2*V4))*(1 + tanh((V-V3)/V4));
beta_m = 0.5*phi* cosh((V-V3)/(2*V4))*(1 - tanh((V-V3)/V4));
end 
end

Answer 1

[Simon Chan]

Move the line function MorrisLecar to be the first line of your entire code.