The integral method used in postprocessing Analysis of Curve fitting tool

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Zhenhui 2011-3-29

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Hi, I want to know what is the exact scheme used in integral function in curve fitting tool. I found that in Help that it calls the function int. and int = integrate(fun,x,x0) integrates the cfit object fun at the points specified by the vector x, starting from x0, and returns the result in int. int is a vector the same size as x. x0 is a scalar.

I still dont know which scheme is used to do the integration, like Simpson quadrature or trapezoidal.

Anyone knows that? Thanks in advance :)

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Answer 1

Andrew Newell 2011-3-30

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在 MATLAB Online 中打开

If you enter

type integrate

you can see the source code. It calls the function quad, which uses adaptive Simpson quadrature.

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Zhenhui 2011-3-30

Thanks Andrew~ i just began learning Matlab to analyze my experimental data, don't know many of its powerful functions. Your answer is really of great help ;)

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Answer 2

Jon Cherrie 2011-3-30

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One of two techniques is used.

For many of the parametric library models, e.g., exponential, Fourier series, the indefinite integral is computed from the coefficients. This is then evaluated to give the definite integral.
For non-parametric models and custom equations, the quad function (adaptive Simpson quadrature) is used.