Unable to find explicit solution

I have this equation which returns "Warning: Unable to find explicit solution" when i use solve on it, the equation and the variabel is symfun. And i am not sure what is wrong?

i have tried dsolve whit no luck same return.

i have tried with and without numerical values

tau_1 = diff(diff(L,diff(theta,t)),t)-diff(L,theta)
tau_m = Dm*(PS-PT)*alpha_m-Bv*diff(theta,t)
equ = tau_1==tau_m

thetadd = diff(theta,t,t);

THETAdd = solve(equ,thetadd)

and if more info is needed it can be provided

if someone have an idea it would help alot thanks

Answer 1

[Bjorn Gustavsson]

This looks like an attempt to derive and solve equations of motion with Euler-Lagrange equations. If that's the case there are tools to facilitate that available on the file exchange: euler-lagrange on FEX. The euler-lagrange-tool-package is the one I think I started using.

HTH

[daniel tarp]

yes it is a Euler-lagrange equation i will look into the toolboks thanks.

[Bjorn Gustavsson]

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