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Student Support Forum: 'data plot, curve fitting, derivatives..' topicStudent Support Forum > General > "data plot, curve fitting, derivatives.."

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emissivity
11/14/12 04:22am

I have the question about curve fitting.

as you see in the link, I have a group of plots like left-most graph.

I used interpolation[~~] but it doesnt fit well.
especially near the point which has zero 2nd derivative.


and, one more, I want 1st derivative graph.
of course, I can get it by solving each points by my hand.

but you know, the programs like mathematica is there for users getting through this easily.

If you can teach me about 1st derivative graph, then I may be able to get 2nd derivative graph.




and..

could you do that by

data = {{0, 1.0}, {2.5, 1.2}, {5.0, 1.3}, {7.5, 1.5}, {10.0,
1.7}, {12.5, 2.0}, {15.0, 7.0}, {17.5, 11.9}, {20.0, 12.1}, {22.5,
12.3}, {25.0, 12.4}, {27.5, 12.5}, {30.0, 12.5}}

?


this is not my real data. just for exercise.




anyway,

1. how to get the good curve which fits well.
2. how to get 1st derivative graph from the data(not from function)



thank you for advance.

URL: http://en.wikipedia.org/wiki/File:Potentiometrics_meas_1st_2nd_deriv-with-legend.JPG,

Subject (listing for 'data plot, curve fitting, derivatives..')
Author Date Posted
data plot, curve fitting, derivatives.. emissivity 11/14/12 04:22am
Re: data plot, curve fitting, derivatives.. Chenyu Lue 11/15/12 05:45am
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