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DSolve stuck (infinite loading) with simple PDEs

Posted 11 months ago

Hey folks!

I'm trying to solve the following equations using DSolve, but it loads indefinitely. Could you please give me some guidance? dD/dt = D * W Entries of D are functions of variables S and t The initial condition of D(S, 0) is given.

But when I solve it inside Mathematica, it keeps loading for more than hours (I tried multiple times, no result after one+ hour)

Thanks a ton! P.S.: my equations are: enter image description here

My DSolve code:

Q[S_, t_] := {
    {d11[S, t], d12[S, t], d13[S, t]}, 
    {d21[S, t], d22[S, t], d23[S, t]}, 
    {d31[S, t], d32[S, t], d33[S, t]}
    }; (*Store results here*)
FullSimplify[Dot[Q[S, t], W]]
Equations = Table[
    D[Q[S, t][[i, j]], t] == FullSimplify[Dot[Q[S, t], W]][[i, j]]
    , {i, 3}, {j, 3}];
InitialConditions = Table[
    Q[S, 0][[i, j]] == FrameEvolve0[[i, j]]
    , {i, 3}, {j, 3}];
sol = Simplify[DSolve[
    Simplify[Flatten[Equations]~Join~InitialConditions], 
    Flatten[Q[S, t]], 
    t]];

I would do it this way:

dd[t_] = Table[d[i, j][t], {i, 3}, {j, 3}];
dd0 = {{-Cos[s], 0, -Sin[s]},
   {-Sin[s], 0, Cos[s]},
   {0, 1, 0}};
w[t_] = (b2 Cos[s])/(c t) {{0, 1, 0},
    {-1, 0, -1}, {0, 1, 0}};
sol = DSolve[{dd'[t] == dd[t] . w[t], dd[0] == dd0},
  Flatten[dd[t]], t]
POSTED BY: Gianluca Gorni
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