6
$\begingroup$

I have a question about exporting an InterpolatingFunction to Excel. I checked the forum, but I still couldn't completely understand how to solve my problem. Could someone help me with this problem?

a = 10^-2;
eq1 = {hf'[t] == -a*(hf[t] - hs[t]),hs'[t] == a*(hf[t] - hs[t]), hf[0] == 20, hs[0] == 0};
sol1 = NDSolve[eq1, {hf, hs}, {t, 0, 100}]

The I got solution for hf[t] & hs[t] :

{{hf -> InterpolatingFunction[{{0.,100.}},<>],
  hs -> InterpolatingFunction[{{0.,100.}},<>]}}

I'm wondering how I can export hf[t] & hs[t] values to excel as t ranges from 0 to 100.

$\endgroup$
8
$\begingroup$
a = 10^-2;
eq1 = {hf'[t] == -a*(hf[t] - hs[t]), hs'[t] == a*(hf[t] - hs[t]),  hf[0] == 20, hs[0] == 0};
sol1 = NDSolve[eq1, {hf, hs}, {t, 0, 100}]

Now:

Plot[{hf[t], hs[t]} /. sol1, {t, 0, 100}]

Mathematica graphics

Export["c:\\test.xls", Table[Flatten[{t, hf[t], hs[t]} /. sol1], {t, 0, 100}]]

Mathematica graphics

$\endgroup$
  • $\begingroup$ Thank you so much for the clear answer! $\endgroup$ – DumbleKo Feb 12 '13 at 22:37
12
$\begingroup$

The interpolating functions that NDSolve returns contain an irregular grid that reflects which points were used to calculate the solution. Not always, but often this grid is a better choice than a regular grid as you would generate with Table when exporting. Here is how you could export the data as NDSolve generated it:

a = 10^-2;
eq1 = {hf'[t] == -a*(hf[t] - hs[t]), hs'[t] == a*(hf[t] - hs[t]), 
   hf[0] == 20, hs[0] == 0};
sol1 = NDSolve[eq1, {hf, hs}, {t, 0, 100}]

hfsol = hf /. First[sol1]
hssol = hs /. First[sol1]

data = {#, hfsol[#], hssol[#]} & /@ First[hfsol@"Coordinates"]
Export[FileNameJoin[{$UserDocumentsDirectory, "sol.xlsx"}], data]
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.