How to make a matrix with one unknown variable, that can be in a for loop and can be used in ODE45
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Hi, at the moment I have the following code. I think the problem is the matrix B is a symbolic funtion, and not a anonymous function, but I can't make an anonymous function to work within a loop.
syms t x u
l=50;
v = 50;
N = 5;
for n = 1:N
for c = 1:N
B(n,c) = sin((n*pi*v*t)/l) * sin((c*pi*v*t)/l);
end
end
T = [t,t,t,t,t];
Td = [diff(t,t) diff(t,t) diff(t,t) diff(t,t) diff(t,t)];
tspan=[1,0.1,10];
xinit=zeros(1,2*N+2);
z=[T u Td diff(u,t)]';
[t,z]=ode45(B*z,tspan,xinit);
It's my first time using the ode45, so I'm not sure I'm using that one correct either.
So now I'm trying the mathworks-community, so I really hope you guys can help!
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回答 (1 件)
Walter Roberson
2019 年 3 月 21 日
See the documentation for odeFunction . In particular, follow the flow of calls that is used in the first example.
6 件のコメント
Walter Roberson
2019 年 3 月 21 日
It is not at all obvious to me that you can justify a finite truncation. That would require that the Tn functions are decaying with increasing n, which is not an obvious conclusion. I can see that it might happen because of the increasing (n*pi/l)^4 multiplier in the first term could force the Tn smaller and smaller to match the right hand side, but the infinite summation makes things difficult.
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