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I have a set of ODEs solved with NDSolve which returns InterpolatingFunctions. When I am trying to plot them, it takes a long time to render. I am guessing that adaptive subdivision for the sharp features makes it slow. My question is: since the interpolation was done internally before NDSolve returns, is there any way we can obtain the list of data points NDSolve used to interpolate? Thanks.

QIZE SHU
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    https://mathematica.stackexchange.com/questions/184132/debugging-ndsolve-to-see-numerical-values-at-each-time-step/184251#184251, https://mathematica.stackexchange.com/questions/28337/whats-inside-interpolatingfunction1-4, https://mathematica.stackexchange.com/questions/151845/taking-part-of-an-interpolatingfunction/152861#152861 – Michael E2 Apr 21 '20 at 19:49
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    Related: https://mathematica.stackexchange.com/questions/134222/easy-way-to-plot-ode-solutions-from-ndsolve – Michael E2 Apr 21 '20 at 19:54

1 Answers1

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iF = y /. NDSolve[{y'[x] == y[x] Cos[x + y[x]], y[0] == 1}, y, {x, 0, 30}][[1]]

enter image description here

You can access the list of Properties of InterpolatingFunction object using

 PropertyList[iF]

 {"Coordinates", "DerivativeOrder", "Domain", "ElementMesh", "Evaluate", 
   "GetPolynomial", "Grid", "InterpolationMethod", "InterpolationOrder", 
   "MethodInformation", "Methods", "OutputDimensions", "Periodicity", "PlottableQ", 
   "Properties", "QuantityUnits", "Unpack", "ValuesOnGrid"}

or

  iF["Methods"]

same list

You can access the property p using iF[p]. For example,

iF["InterpolationOrder"]

 {3}

iF["Coordinates"] // Short[#, 3] &

enter image description here

iF["Grid"] // Short[#, 3] &

enter image description here

iF["ValuesOnGrid"] // Short[#, 3] &

enter image description here

etc.

kglr
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