function not plotting, but no error message

Question

Jon 2023-9-27

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2026574-function-not-plotting-but-no-error-message

评论： Dyuman Joshi 2023-9-27

采纳的回答： Dyuman Joshi

I created this function and plot but it is not plotting and I am not getting any error message.

%x1'=-3x1-200x2

%x2'=200x1-3x2

opts = odeset('RelTol',1e-6,'AbsTol',1e-8);function [dXdt] = Problem02ODEFunction(t,X)

soln = ode45(@Problem02ODEFunction,[0 1],[-10 10],opts);

figure;

plot(soln.x,soln.y(1,:),'-','linewidth',0.5);

hold on;

plot(soln.x,soln.y(2,:),'-','linewidth',0.5);

grid on;

title('Problem 2 ODE45 Solution');

xlabel('Time (s)');

ylabel('Solution');

legend('x_{1}(t)','x_{2}(t)','location','best');

function [dXdt] = Problem02ODEFunction(t,X)

x1 = X(1);

x2 = X(2);

dx1dt = -3*x1 - 200*x2;

dx2dt = 200*x1 - 3*x2;

[dXdt] = [dx1dt; dx2dt];

end

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Answer 1

Dyuman Joshi 2023-9-27

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2026574-function-not-plotting-but-no-error-message#answer_1320364

在 MATLAB Online 中打开

The code after the semi-colon in this line of code seems to be a typo

opts = odeset('RelTol',1e-6,'AbsTol',1e-8);function [dXdt] = Problem02ODEFunction(t,X)

After removing it, the code works and the plots are there -

%x1'=-3x1-200x2

%x2'=200x1-3x2

opts = odeset('RelTol',1e-6,'AbsTol',1e-8);

soln = ode45(@Problem02ODEFunction,[0 1],[-10 10],opts)

soln = struct with fields:

solver: 'ode45' extdata: [1×1 struct] x: [0 2.4865e-04 0.0013 0.0023 0.0033 0.0041 0.0048 0.0055 0.0064 0.0073 0.0083 0.0093 0.0103 0.0112 0.0121 0.0127 0.0135 0.0143 0.0153 0.0162 0.0173 0.0183 0.0192 0.0199 … ] (1×1148 double) y: [2×1148 double] stats: [1×1 struct] idata: [1×1 struct]

figure;

plot(soln.x,soln.y(1,:),'-','linewidth',0.5);

hold on;

plot(soln.x,soln.y(2,:),'-','linewidth',0.5);

grid on;

title('Problem 2 ODE45 Solution');

xlabel('Time (s)');

ylabel('Solution');

legend('x_{1}(t)','x_{2}(t)','location','best');

function dXdt = Problem02ODEFunction(t,X)

x1 = X(1);

x2 = X(2);

dx1dt = -3*x1 - 200*x2;

dx2dt = 200*x1 - 3*x2;

[dXdt] = [dx1dt; dx2dt];

end

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Jon 2023-9-27

MAT330_Project_2.pdf

for this class project they want us doing it in live editor, I removed that semicolon and it still doesn't plot. I shared the whole .mlx file, maybe something else you see is causing a conflict.