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Student Support Forum: 'NDSolve errors' topicStudent Support Forum > General > "NDSolve errors"

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Author Comment/Response
Max
09/05/06 2:06pm

Hello everyone,
I'm trying to numerically solve a differential equation of the form:

u[z] u'[z]==C1+(-C2*(C3-z)/z)(C4+C5 u[z]
with a boundary condition u[-C6]==0

I first get the error Power::infy : Infinite expression 1/0. encountered

and then the error
NDSolve::ndum : encountered non-numerical value for a derivative at z=-C6...

Any help understanding the second message would be much appreciated.

Thanks,
Max

Here is the actual NDSolve input:


\!\(\*
RowBox[{"NDSolve", "[",
RowBox[{
RowBox[{"{",
RowBox[{
RowBox[{
RowBox[{\(u[z]\), " ",
RowBox[{
SuperscriptBox["u", "?",
MultilineFunction->None],
"[", "z", "]"}]}],
"==", \(\(\(9.8`\)\(\[InvisibleSpace]\)\) - \
\(0.00025700061842918987`\ \((273 -
z\/50)\)\ \((\(\(29400.000000000004`\)\(\[InvisibleSpace]\)\) \
+ 900\ u[z])\)\)\/z\)}], ",", \(u[10000] == 0\)}], "}"}], ",", "u", ",", \({z,
10, 100}\)}], "]"}]\)


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