Hi 旭龙,

That is strange. If you look at InputForm@iFunc and compare it with the file iFunc.wl (it is a text file) you will see that the InputForm includes a long list of numbers like 5.715581102622704*^11 at the end. I have no idea what those numbers are. What matters is that the expressions are identical. I would trust Equal more than some approximate number computed by the frontend.

If you are still concerned, generate some random rational numbers within the domain of the interpolating function and evaluate both functions at that value and compare the result.

Hi, Rohit! I trided what you told me last time. Though iFunc == iFuncNew gave True result, the sizes of them differed: 3.5M(initial) and 2.2M(New). Next are the screenshots:

The function SOMA[] is

Nice method, thank you! What if the InterpolatingFunction[] is given by NDSolve solution? Or similarly, just rationalize the equations first?

Hi 旭龙

I rarely make use of the "Data not in notebook; Store now" feature. It can significantly increase the size of the notebook resulting in slow loading/saving time. If you want to save the results of computations for use later in a different session then take a look at Save and Get. e.g.

SetDirectory[NotebookDirectory[]]
iFunc = Interpolation@Rationalize[data, 0]
Save["iFunc.wl", iFunc]

Close notebook, quit kernel or restart Mathematica

SetDirectory[NotebookDirectory[]]
ClearAll@iFunc
Get["iFunc.wl"]
iFunc

This will also work for persisting the solutions from NDSolve. The round-trip from Save to Get should not cause any loss of precision. If you find it does, it is a bug. e.g. you can try this

ClearAll@iFunc
Get["iFunc.wl"]
iFuncNew = Interpolation@Rationalize[data, 0]
iFunc == iFuncNew
(* True *)