Fit a curve of equation of form y = ax^b to data

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Ershad Ahamed Chemmalasseri
回答： hitesh Mehta 2018-2-17
Hi,
How do I fit a curve of equation of form y = ax^b to my data. I have x and y values. I have to find a and b (it can be a fraction) and plot the curve.

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采纳的回答

Honglei Chen
Honglei Chen 2012-6-19
If you have Curve Fitting Toolbox, you can use that to do an exponential fitting directly
http://www.mathworks.com/help/toolbox/curvefit/bszh0sy-5.html
If not, you can take logarithm of both sides and translate that into a linear fitting problem, i.e.
log(y) = log(a)+b*log(x)
and then use polyfit
http://www.mathworks.com/help/techdoc/ref/polyfit.html

更多回答（2 个）

Sean de Wolski
Sean de Wolski 2012-6-19
Any of these are designed for this.
  • lsqcurvefit Optimization Toolbox
  • nlinfit Statistics Toolbox
  • NonlinearModel Statistics Toolbox >= R2012a.
hitesh Mehta
hitesh Mehta 2018-2-17
Hi,
How do I fit a curve of equation of form y = ax^b+c to my data. I have x and y and c values.
I have to find a and b(it can be a fraction) and plot the curve.

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