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Error using NDEigensystem output as initial condition of NDSolve

Posted 10 months ago
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Hi, I used NDEigensystem to find eigenfunctions of an operator as shown below.

{vals, funs} = 
NDEigensystem[{-\[Pi] D[g[x], {x, 2}] - 0.05Cos[x] g[x] , 
DirichletCondition[g[x] == 0, True]}, g[x], {x, -\[Pi], \[Pi]}, 4]

I then used one of the eigenfunctions obtained from here as an initial condition in a differential equation as shown below

NDSolve[{I D[f[x, t], t] == -D[f[x, t], {x, 2}]/2 - 
0.05 (1 + Cos[t]) Cos[x] f[x, t], 
f[x, 0] == funs[[2]][x]}, f, {x, -\[Pi], \[Pi]}, {t, 0, 2 \[Pi]}]

But I keep getting the error


There are no problems in using the eigenfunction for plots etc. Also when I use a different initial condition I get back a reasonable solution. Only when I use the eigenfunction as an initial condition for this do I get a problem. Can someone help with this please?

POSTED BY: conan alexander
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