dimensionality problem with differential equations

Question

Ruben 2011-4-26

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/6243-dimensionality-problem-with-differential-equations

采纳的回答： Andrei Bobrov

在 MATLAB Online 中打开

Hello,

when trying to solve a set of 2 differential equations, matlab gives me the following error:

??? In an assignment A(I) = B, the number of elements in B and I must be the same.

the code is as follows:

tspan = [0 tijd];
initialvalues = [0; 0];
[X,Y] = ode45(@dvgl,tspan,initialvalues);

with dvgl.m as follows:

k = 12.6651;
I2 = 0.516e-2;
dy = zeros(2,1);
dy(1) = y(2); % y(1) = theta2
dy(2) = 1./I2*((omega1./y(2)).*T1-k.*y(1)); % y(2) = omega2

omega1 is a 1 by 1667 vector. All te rest are scalars

Your help would be much appreciated.

Sincere regards,

Ruben

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Answer 1

Andrei Bobrov 2011-4-26

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/6243-dimensionality-problem-with-differential-equations#answer_8652

在 MATLAB Online 中打开

variant

I'm sorry I made a T1 variable: t = T1

dvgl = @(t,y,omega,k,I2)[y(2); 1./I2*((omega1./y(2)).*t-k.*y(1))];
k = 12.6651;
I2 = 0.516e-2;
tspan = [0 tijd];
initialvalues = [0; 0];
XY = cell(length(omega),2);
for j = 1:length(omega)
    [XY{j,1},XY{j,2}] = ode45(@(t,y)dvgl(t,y,omega(j),k,I2),tspan,initialvalues);
end