I have a 14 equation system of second order differential equations which I am trying to solve using dsolve. The program just keeps running without finishing ?
2 views (last 30 days)
Show older comments
This is the script: A is 14x14 matrix
syms x1(t) x2(t) x3(t) x4(t) x5(t) x6(t) x7(t) x8(t) x9(t) x10(t) x11(t) x12(t) x13(t) x14(t);
X = [x1;x2;x3;x4;x5;x6;x7;x8;x9;x10;x11;x12;x13;x14];
syms E;
syms alpha;
f = [(k/m) * E * cos(alpha*t);0;0;0;0;0;0;0;0;0;0;0;0;0];
odes = diff(X,2) == A*X + f;
%odes = diff(X,2) == A*X;
%V = odeToVectorField(odes)
%M = matlabFunction(V,'vars',{'t','E','alpha','Y'})
[x1Sol(t),x2Sol(t),x3Sol(t),x4Sol(t),x5Sol(t),x6Sol(t),x7Sol(t),x8Sol(t),x9Sol(t),x10Sol(t),x11Sol(t),x12Sol(t),x13Sol(t),x14Sol(t)] = dsolve(odes);
x1Sol(t) = simplify(x1Sol(t))
x2Sol(t) = simplify(x2Sol(t))
x3Sol(t) = simplify(x3Sol(t))
x4Sol(t) = simplify(x4Sol(t))
x5Sol(t) = simplify(x5Sol(t))
x6Sol(t) = simplify(x6Sol(t))
x7Sol(t) = simplify(x7Sol(t))
x8Sol(t) = simplify(x8Sol(t))
x9Sol(t) = simplify(x9Sol(t))
x10Sol(t) = simplify(x10Sol(t))
x11Sol(t) = simplify(x11Sol(t))
x12Sol(t) = simplify(x12Sol(t))
x13Sol(t) = simplify(x13Sol(t))
x14Sol(t) = simplify(x14Sol(t))
Would really appreciate help on this.
4 Comments
Answers (1)
darova
on 29 Nov 2019
alpha and E should be numerical
function main
m = 15000;
k = 150000;
n = 14;
A = zeros(n);
A(n,n) = -k/m;
A(n,n-1) = k/m;
for i=1:n-1
A(i,i) = -2*k/m;
A(i+1,i) = k/m;
A(i,i+1) = k/m;
end
f = zeros(n,1);
x0 = ones(2*n,1);
ts = [0 5];
[t,X] = ode45(myode,ts,x0);
plot(t,X)
function dx = myode(t,x)
dx = zeros(2*n,1);
f(1) = k/m * E * cos(alpha*t);
dx(1:n) = x(n+1:end);
dx(n+1:end) = A*x(1:n) + f;
end
end
2 Comments
See Also
Categories
Find more on Equation Solving in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!