# Getting numerical values from integrated interpolating function [duplicate]

I have a list of data. I integrate them with interpolation. Lets say is the following:

  InterpolatingFunction[{{0.01, 4.82}}, <>][x]


However, is that anyway for me to get an array of coordinates of the function after integration?

Thank you

I am not quite sure what you want but this may help. First I generate some data

data = Table[{x, x + Sin[2 \[Pi] x]}, {x, 0.01, 4.82, 0.1}];


This plots as

ListPlot[data, Frame -> True, PlotTheme -> "Scientific"]


Now we make an interpolation function and then integrate

f = Interpolation[data];
g = Integrate[f[x], x]


Interestingly the x from the integration gets built in to the new fuction. Someone might like to explain this

I remove the [x] at the end by taking the head

g1 = Head[g];


Now we can plot the integrated function

p1 = Plot[g1[x], {x, 0.01, 4.82}, Frame -> True,
PlotTheme -> "Scientific"]


If we want to go back to coordinates then there are several ways. If we wish to use the same x values as before then can do the following

cc = Transpose[{data[[All, 1]], g1[#] & /@ data[[All, 1]]}];


and plot

Show[p1, ListPlot[cc, PlotStyle -> {Green}]]


Is this what you are after?

• Yes! thank you very much!!!:) Nov 8, 2015 at 1:15
• @YinchengLiu I am glad I could help. The usual procedure is for you to accept the answer by applying the tick and thus closing the discussion.
– Hugh
Nov 8, 2015 at 7:31