My curve is not fitting

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@km
@km 2017-10-25
评论： @km 2017-11-10
Hello All, I am trying to fit my experimental data with an analytical equation. I am attaching my data and the code that I used. I am doing some mistake. But I am not able to solve it. Thanks in advance for your help.

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Walter Roberson
Walter Roberson 2017-10-25
The coefficients that it comes up with are pretty close to the best you can get for that equation. The best coefficients are quite close to a = 774.958449381415 b = 0.000201392498068715, which I determined by sweeping a lot of the search space. The residual is on the order of 3.48E-9. Coefficients in the range of a = 550-ish with b as large as 45 can give a residual on the order of 7E-9 which is really not bad: it just happens that there is a narrow range above 750 that can do better on a relative scale.
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Walter Roberson
Walter Roberson 2017-10-25
If your data values are not to be considered noise, then the conclusion would seem to be that the function you give to fit to is not a function that describes the curve to the degree that you would like.
Given that particular function, your existing code already finds very nearly the best coefficients that can be found for that data.
@km
@km 2017-11-10
You were right that there was a problem in the analytical model. Thanks for the help. Apologies for the late reply as i wanted some strong conclusion before starting a different approach.

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