Timeline for shooting method and stiffness problem for NDSolve
Current License: CC BY-SA 3.0
4 events
| when toggle format | what | by | license | comment | |
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| Dec 19, 2013 at 3:02 | comment | added | xzczd♦ | @sam84 I believe what you need is still a better initial condition, though I can't find it now :). As I mentioned above, you may have a hard time searching a proper initial condition. See this and this for example. | |
| Dec 18, 2013 at 17:35 | comment | added | sam84 | In fact the complete problem is k = 1; eqn = 1/r[x]^5 + k/Sqrt[1 + r'[x]^2] - (k r[x] r''[x])/(1 + r'[x]^2)^(3/2); sf = NDSolve[{eqn == 0, r[3] == 25, r[149] == 45}, r, {x, 3, 149}, Method -> {"Shooting", "StartingInitialConditions" -> {r[3] == 25, r'[3] == 1}}, WorkingPrecision -> 16]; But the solution gives me r[3] /. sf =105.2684511703500 | |
| Dec 18, 2013 at 17:33 | comment | added | sam84 | You are right, initial conditions are crucial and with r[0]==1, r'[0]==1, the solution is easily obtained. But if for instance I put the constraint r[10]==10, instead of r[1]=10, the solution is not able anymore to satisfy the constrain I impose. | |
| Dec 17, 2013 at 12:42 | history | answered | xzczd♦ | CC BY-SA 3.0 |