maple

[alejandrito20]

For my thesis I need to solve many differential equations non linear, second order by using maple....

For example figure adjoint

using dsolve command, the solutions are very extensives and very bad.

 

there is a suggest for to solve the differential equations by using maple?

 

there is some methods in maple to find the aproximate solution?

 

thanks

[the tree]

It would be helpful if you could include the Maple code rather than leaving us to transpose it. I figured it was something like:

(
 -2*exp( -3*f(t))*Diff(f(t),t)^2
 +2*exp( -3*f(t))*Diff(f(t),t,t)
 +3*exp( -2*f(t))*Diff(f(t),t)^4
 +2*sqrt( (-1+ exp(f(t))*(Diff(f(t),t)^2 ))*exp(-4*f(t))  )
 *sqrt( -(exp(-f(t)) - Diff(f(t),t)^2*exp(-f(t)) ))
 *exp(-f(t))
)/
(
 (exp(-f(t)) - (Diff(f(t),t))^2 )
 *sqrt( (-1 + Diff(f(t),t)^2 )*exp(-4*f(t)) )
 *sqrt(-(exp(f(t)) - Diff(f(t),t)^2 ) * exp(-3*f(t))  )
)
= 0;

Which could easily be wrong.

From there I would suggest manually simplifying the expression (simple things like [imath]\sqrt{a}\sqrt{b}=\sqrt{ab}[/imath]) and maybe replacing the [imath]e^{-n f(t))}[/imath] with a new function, then letting Maple solve the pair of them as a system of equations.

[alejandrito20]

you say this?

if exp(-f(t))=c(t) then

 

a := (-2*c(t)^3*(Diff(f(t), t))^2
+2*c(t)^3*(Diff(f(t), t, t))
+3*c(t)^2*(Diff(f(t), t))^4
+2*sqrt((-1+c(t)^(-1)*(Diff(f(t), t))^2)*c(t)^4*(-c(t))
+(Diff(f(t), t))^2*c(t)))*c(t)/((c(t)
-(Diff(f(t), t))^2)*sqrt(((-1+(Diff(f(t), t))^2)*c(t)^4)
*(-(c(t))-(Diff(f(t), t))^2)*c(t)^3)) = 0;

 

but

    dsolve(a,c(t)); maple says error... 

    dsolve(a,f(t)); maple shows a bas solution and extensive... 

 

sorry for not understanding. I'm starting to use maple