I am trying to solve the following differential equation-
k = NDSolve[{y'''[x] == -76*Sin[y[x]], y[0] == Pi/4, y'[0] == 0,
y[1.85] == 0}, y, {x, 0, 2}, AccuracyGoal -> 10,
PrecisionGoal -> 30]
I am getting a solution but when I plot a graph, it does not satisfy the boundary conditions. I am getting the following two errors- FindRoot::sszero: The step size in the search has become less than the tolerance prescribed by the PrecisionGoal option, but the function value is still greater than the tolerance prescribed by the AccuracyGoal option. >>
NDSolve::berr: There are significant errors {-0.239832,-0.0591905,-0.0015434} in the boundary value residuals. Returning the best solution found. >>
The funny thing is when I reduce the coefficient of Sin[y[x]]
it works fine. Can anyone help me with this?
Thanks,
y[1.85] == 0
byy''[0] == c
, and then varyc
to see what value ofy[1.85]
it gives rise to. I found thaty[1.85]
rapidly switches between negative and positive values asc
increases from 24.4 to 24.5, so your solution lies somewhere in that range. The optimisation ofc
should be automated, but I haven't got time right now. $\endgroup$