Timeline for Problem with fitting
Current License: CC BY-SA 4.0
12 events
| when toggle format | what | by | license | comment | |
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| May 22, 2021 at 7:05 | history | edited | Carl Lange |
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| May 21, 2021 at 21:25 | vote | accept | John | ||
| May 21, 2021 at 21:15 | answer | added | JimB | timeline score: 3 | |
| May 21, 2021 at 21:05 | comment | added | John |
@AlexeiBoulbitch try for example: fun[x_] = NonlinearModelFit[ Tinficryst /. {x_, y_} -> {x + 273.15, y}, {eq, c1 == -65514626.3392678, c2 == 68.393062008793}, {c1, c2}, x] // Normal; you will see that by making c1 and c2 those values the fit are good. However, Mathematica does not find the value of -65514626.339267 for c1 or the value of 68.393062008793 for c2
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| May 21, 2021 at 21:04 | comment | added | Alexei Boulbitch | I do not see that. Try to look at the plot (the code from my first comment) with your new data. | |
| May 21, 2021 at 20:28 | history | edited | John | CC BY-SA 4.0 |
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| May 21, 2021 at 19:29 | comment | added | John | @AlexeiBoulbitch I have updated the data. I think the reason it was not working is because the y axis of the data was in log scale. I have updated the data now. I think now the c1 and c2 values that I found in excel are the ones that fit the data but still Mathematica does not find it | |
| May 21, 2021 at 19:28 | history | edited | John | CC BY-SA 4.0 |
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| May 21, 2021 at 19:23 | comment | added | Alexei Boulbitch | Often such things indicate that the model is not optimal. I would try to think about another to fit the data. | |
| May 21, 2021 at 19:05 | comment | added | John | @AlexeiBoulbitch thank you for you comment. Then what would the best fit be? and why Mathematica cannot find it? | |
| May 21, 2021 at 18:13 | comment | added | Alexei Boulbitch |
Try to plot this: Show[{ ListPlot[data], Plot[(E^(2595.89/(-259.246 + x)))^0.75/(c1 (1 - E^(5.092118394960718*^-6 c2 (443.15 - x))) x) /. {c1 ->313634, c2 -> -8434.47}, {x, First[data][[1]], Last[data][[1]]}, PlotRange -> All]. It shows that the values of c1 and c2 you obtained from excel yield a very bad fit, if any.
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| May 21, 2021 at 16:42 | history | asked | John | CC BY-SA 4.0 |