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[✓] Solve coupled differential-algebraic equations (Stiff-system suspected)

GROUPS:

I am trying to plot a graph between eta and tau using NDSolve method . But i am getting the message at output 'Stiff-system suspected'. Kindly help me to solve the problem

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POSTED BY: shivi sv
Answer
1 month ago

Define each of your functions

functionName[parameter_] := definition

instead of

functionName[parameter] = definition

and then make the following changes to the end of your notebook

s = NDSolve[{a'[τ]-Sqrt[A*(1-1/a[τ])+B1*Log[a[τ]]]==0, a[0]==1.05}, {a[τ]}, {τ,0,.05}][[1]];

t2 = Plot[a[τ]/.s, {τ,0,0.05}, PlotStyle->{Thickness[0.006]}, AxesLabel->{τ,a}, PlotRange->{0,20}]

eta[τ_] := Abs[α[τ]/f[τ]]/.s;

t3 = Plot[eta[τ], {τ,0,0.02}, PlotStyle->{Thickness[0.006]}, AxesLabel->{τ,eta}, PlotRange->All]

Plot[Im[α[τ]]/.s, {τ,0,0.02}, PlotStyle->{Thickness[0.006]}, AxesLabel->{τ,Im[α]}]

Plot[f[τ]/.s, {τ,0,0.02}, PlotStyle->{Thickness[0.006]}, AxesLabel->{τ,f}]

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POSTED BY: Bill Simpson
Answer
1 month ago

Group Abstract Group Abstract