0
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z := 0.0000000000001

LE = NDSolve [{(2/ξ) θ'[ξ] + θ''[ξ] +  θ[ξ]^3 == 0, θ[z] == 1, θ'[z] == 0}, 
              θ[ξ], {ξ, z, 10}]; 

Plot[ Evaluate[{θ[ξ], θ'[ξ], θ''[ξ]} /. LE], {ξ, 0, 10}, AxesLabel -> {ξ, θ}]

f[ξ_] = Evalute[θ[ξ] /. LE]; 

Manipulate[NSolve[f[n]], {n, 0, 7}]

FindRoot[f[ξ], {ξ, 7}]

And I get, FindRoot::nlnum: The function value {Evalute[{-0.00431221}]} is not a list of numbers with dimensions {1} at {[Xi]} = {7.}. >>

Why?

Thanks in advance!

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closed as off-topic by wxffles, bbgodfrey, Sjoerd C. de Vries, Verbeia Apr 24 '15 at 7:06

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "This question arises due to a simple mistake such as a trivial syntax error, incorrect capitalization, spelling mistake, or other typographical error and is unlikely to help any future visitors, or else it is easily found in the documentation." – wxffles, bbgodfrey, Sjoerd C. de Vries, Verbeia
If this question can be reworded to fit the rules in the help center, please edit the question.

  • $\begingroup$ You can format inline code and code blocks by selecting it and clicking the {} button above the edit window. The edit window help button ? is also useful for learning how to format your questions and answers. $\endgroup$ – Michael E2 Apr 24 '15 at 2:28
  • 1
    $\begingroup$ Because you spelled Evaluate wrong? $\endgroup$ – wxffles Apr 24 '15 at 2:33
2
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z = 0.0000000000001;

le = NDSolve[{(2/x) t'[x] + t''[x] + t[x]^3 == 0, t[z] == 1, 
     t'[z] == 0}, t[x], {x, z, 10}][[1, 1]];

led = NestList[D[#, x] &, le, 2];

Plot[Evaluate[{t[x], t'[x], t''[x]} /. led], {x, z, 10},
 AxesLabel -> {x, t},
 PlotRange -> {-0.5, 1.1},
 PlotLegends -> {"t(x)", "t'(x)", "t''(x)"}]

enter image description here

Clear[f];

f[x_?NumericQ] := Evaluate[t[x] /. le]

Off[NSolve::ifun];

NSolve[f[x] == 0, x][[1]]

{x -> 6.89685}

FindRoot[f[x], {x, 6}]

{x -> 6.89685}

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