Matlab help
Matlab help
(OP)
Matlab can solve a set of non linear coupled equation; I want to find the third order solution, does anyone have a typical program for such Problem:
dx11/dt=a*x11*y12+b*y12
dy12/dt=c*y12*x11+d*x11
where a , b,c,d are constants
I want to see just the third order solution
dx11/dt=a*x11*y12+b*y12
dy12/dt=c*y12*x11+d*x11
where a , b,c,d are constants
I want to see just the third order solution





RE: Matlab help
If you have initial values, you can solve by ode45.
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(2B)+(2B)' ?
RE: Matlab help
RE: Matlab help
It seems to me you have a non-linear, coupled, differential equation. But if you're only interested in a 3rd order polynomial solution, then you can evaluate the derivative, like so:
Let x11 = x(t), y12 = y(t).
Assume x(t) = A + Bt + Ct^2 and y(t) = D + Et + Ft^2.
Then your coupled equations are just:
B + 2Ct = a(A + Bt + Ct^2)(D + Et + Ft^2) + b(D + Et + Ft^2)
E + 2Ft = c(A + Bt + Ct^2)(D + Et + Ft^2) + d(A + Bt + Ct^2)
Expand and equate coefficients and you'll have 10 linear equations in 6 unknowns. Should be relatively easy to solve numerically from there.