c****l
发帖数: 88 | 1 Hi,
I am using Mathematica to numercially solve the following equations:
2 D[f0[r], r]/r + D[f0[r], r, r] == -2 A f1[r]/r^4 + 2 A D[f1[r], r]/r^3
-2 f1[r]/r^2 + 2 D[f1[r], r]/r + D[f1[r], r, r] == 2 A D[f0[r], r]/r^3
And my boundary condition is
f0[10] == 0.01, f1[10] == 0.01, (D[f0[r], r] /. r -> 1) == 10^-3 A,
(D[f1[r], r] /. r -> 1) == 0
When I take A to be small, say 1, everything is fine. However, if I take A
to be large, e.g. 100. Mathematica complains and gives me crazy results.
Here are the error message I get:
NDSolve::bvluc: The equations derived from the boundary conditions are
numerically ill-conditioned. The boundary conditions may not be sufficient
to uniquely define a solution. The computed solution may match the boundary
conditions poorly. >>
NDSolve::berr: There are significant errors {-5.55116*10^6,-7.26312*10^6,0.,
0.} in the boundary value residuals. Returning the best solution found. >>
Can anyone help me to deal with this issue? I appreciate your help!
Thanks! | S*********k
发帖数: 507 | 2 Such questions could go to mathematica.stackexchange.com
Any reasonablly answerable questions will be answered fairly promptly.
A
【在 c****l 的大作中提到】
: Hi,
: I am using Mathematica to numercially solve the following equations:
: 2 D[f0[r], r]/r + D[f0[r], r, r] == -2 A f1[r]/r^4 + 2 A D[f1[r], r]/r^3
: -2 f1[r]/r^2 + 2 D[f1[r], r]/r + D[f1[r], r, r] == 2 A D[f0[r], r]/r^3
: And my boundary condition is
: f0[10] == 0.01, f1[10] == 0.01, (D[f0[r], r] /. r -> 1) == 10^-3 A,
: (D[f1[r], r] /. r -> 1) == 0
: When I take A to be small, say 1, everything is fine. However, if I take A
: to be large, e.g. 100. Mathematica complains and gives me crazy results.
: Here are the error message I get:
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