Matlab coding ordinary differential equation initial condition graph not running in the initial condition

Question

Dhivyadharshini 2025-9-29

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2180252-matlab-coding-ordinary-differential-equation-initial-condition-graph-not-running-in-the-initial-cond

编辑： Torsten 2025-9-29

Matlab coding ordinary differential equation initial condition graph not running in the initial condition. For x(2), x(6) and x(7) only getting properly graph is coming with the initial condition starting but for x(1), x(3), x(4), x(5) graph is not coming as the initial condition starting

Tr()

30 successful steps 2 failed attempts 193 function evaluations Elapsed time is 0.072265 seconds.

function Tr

options = odeset('RelTol',1e-6,'Stats','on');

%initial conditions

Xo = [0.005; 0.0007; 0.001; 0.0001; 0.0001; 0; 0];

tspan = [0,120];

tic

[t,X] = ode45(@TestFunction,tspan,Xo,options);

toc

%figure

hold on

plot(t, X(:,1), 'green')

plot(t, X(:,2), 'blue')

plot(t, X(:,3), 'red')

plot(t, X(:,4), 'yellow')

plot(t, X(:,5), 'green')

plot(t, X(:,6), 'cyan')

plot(t, X(:,7), 'y')

%hold on

% legend('x1','x2')

% ylabel('x - Population')

% xlabel('t - Time')

%hold on

end

function [dx_dt]= TestFunction(~,x)

% Parameters

s = 0.038;

alpha = 0.02;

gamma = 0.10;

r = 0.03;

dH = 0.0083;

dX = 0.0125;

rho = 0.07;

K = 500;

beta = 0.0005;

theta = 0.03;

eta = 0.015;

muH = 0.015;

muI = 0.08;

lambdaP = 0.05;

lambdaL = 0.043;

UP = 0.20;

deltaP = 0.033;

UL = 0.50;

deltaL = 0.05;

kappa = 0.005;

dx_dt(1) = (s) - ((alpha * x(3) * x(1)) / (1 + gamma * x(1))) - (dH * x(1)) + (r * x(2));

dx_dt(2) = ((alpha * x(3) * x(1)) / (1 + gamma * x(1))) - ((r+dX) * x(2));

dx_dt(3) = ((rho * x(3)) * (1 - (x(3) + x(4)) / K)) - (beta * x(3) * x(5)) - (lambdaP * x(6) * x(3)) - (lambdaL * x(7) * x(3)) - (muH * x(3));

dx_dt(4) = (beta * x(3) * x(5)) - (lambdaP * x(6) * x(4)) - (lambdaL * x(7) * x(4)) - (muI * x(4)) - (kappa * x(5) * x(4));

dx_dt(5) = (theta * x(4)) - (eta * x(5));

dx_dt(6) = (UP) - (deltaP * x(6));

dx_dt(7) = (UL) - (deltaL * x(7));

dx_dt = dx_dt';

end

%hold on

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Sam Chak 2025-9-29

编辑：Torsten 2025-9-29

在 MATLAB Online 中打开

Hi @Dhivyadharshini

The responses for x1, x3, x4, and x5 begin from the specified initial values: {0.005, 0.001, 0.0001, 0.0001}.

options = odeset('RelTol', 1e-6);

X0 = [0.005; 0.0007; 0.001; 0.0001; 0.0001; 0; 0];

% x1 x2 x3 x4 x5 x6 x7

tspan = [0, 120];

[t, X] = ode45(@TestFunction, tspan, X0, options);

% figure(1)

% tL = tiledlayout(2, 2, 'TileSpacing', 'Compact');

%

% nexttile

% plot(t, X(:,1), 'color', '#AA0815'), grid on

% title('x1')

%

% nexttile

% plot(t, X(:,3), 'color', '#F0B41C'), grid on

% title('x3')

%

% nexttile

% plot(t, X(:,4), 'color', '#49B6A9'), grid on

% title('x4')

%

% nexttile

% plot(t, X(:,5), 'color', '#3D9BE1'), grid on

% title('x5')

%

% xlabel(tL, 'Time')

% ylabel(tL, 'Population')

figure(2)

tL2 = tiledlayout(2, 2, 'TileSpacing', 'Compact');

nexttile

plot(t, X(:,1), 'color', '#AA0815'), grid on

xlim([0, 120])

title('x1')

nexttile

plot(t, X(:,3), 'color', '#F0B41C'), grid on

xlim([0, 120])

title('x3')

nexttile

plot(t, X(:,4), 'color', '#49B6A9'), grid on

xlim([0, 120])

title('x4')

nexttile

plot(t, X(:,5), 'color', '#3D9BE1'), grid on

xlim([0, 120])

title('x5')

%title(tL2, 'Zoomed-in')

xlabel(tL2, 'Time')

ylabel(tL2, 'Population')

%% Dynamics of Population Growth

function [dx_dt]= TestFunction(~,x)

% Parameters

s = 0.038;

alpha = 0.02;

gamma = 0.10;

r = 0.03;

dH = 0.0083;

dX = 0.0125;

rho = 0.07;

K = 500;

beta = 0.0005;

theta = 0.03;

eta = 0.015;

muH = 0.015;

muI = 0.08;

lambdaP = 0.05;

lambdaL = 0.043;

UP = 0.20;

deltaP = 0.033;

UL = 0.50;

deltaL = 0.05;

kappa = 0.005;

dx_dt(1) = (s) - ((alpha * x(3) * x(1)) / (1 + gamma * x(1))) - (dH * x(1)) + (r * x(2));

dx_dt(2) = ((alpha * x(3) * x(1)) / (1 + gamma * x(1))) - ((r+dX) * x(2));

dx_dt(3) = ((rho * x(3)) * (1 - (x(3) + x(4)) / K)) - (beta * x(3) * x(5)) - (lambdaP * x(6) * x(3)) - (lambdaL * x(7) * x(3)) - (muH * x(3));

dx_dt(4) = (beta * x(3) * x(5)) - (lambdaP * x(6) * x(4)) - (lambdaL * x(7) * x(4)) - (muI * x(4)) - (kappa * x(5) * x(4));

dx_dt(5) = (theta * x(4)) - (eta * x(5));

dx_dt(6) = (UP) - (deltaP * x(6));

dx_dt(7) = (UL) - (deltaL * x(7));

dx_dt = dx_dt';

end

Dhivyadharshini 2025-9-29

I want for 120 days x-axis 120 should come

Torsten 2025-9-29

编辑：Torsten 2025-9-29

Then adapt the "xlim" commands in the code (see above).

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Matlab coding ordinary differential equation initial condition graph not running in the initial condition

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Matlab coding ordinary differential equation initial condition graph not running in the initial condition

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