how to subplot a predation model with global variables in matlab in javascript

main.m
% Define global variables
global pop_x pop_y prey_color pred_color

% Set initial values for global variables
pop_x = 0:0.1:20;   % x-axis values for population
prey_color = 'r';   % color for prey line
pred_color = 'b';   % color for predator line

% Define your predation model function
function dx = predation_model(~, x, a, b, c, d)
    global pop_x pop_y prey_color pred_color
    
    % Update population values
    pop_y = x;
    
    % Compute population derivatives
    f = [a*x(1) - b*x(1)*x(2);
         -c*x(2) + d*x(1)*x(2)];
    
    % Plot prey and predator populations
    subplot(2, 1, 1);
    plot(pop_x, pop_y(:, 1), prey_color);
    xlabel('Time');
    ylabel('Prey');
    title('Population dynamics of prey and predators');
    
    subplot(2, 1, 2);
    plot(pop_x, pop_y(:, 2), pred_color);
    xlabel('Time');
    ylabel('Predator');
    
    % Return population derivatives to ODE solver
    dx = f';
end

% Define parameter values
a = 0.5;
b = 0.05;
c = 0.2;
d = 0.004;

% Define initial population values
x0 = [100, 15];

% Solve the ODE using ode45 solver
[t, x] = ode45(@(t,x) predation_model(t,x,a,b,c,d), [0 20], x0);

% Display figure with both subplots
figure();
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