sfit object. can't get coefficients.

Question

almaz ham 2015-3-3

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/181171-sfit-object-can-t-get-coefficients

评论： maitehar 2020-6-8

Hello. There is my code:

>> c = fit( [X, Z], Y, ft, opts );
>> c
       Linear interpolant:
         c(x,y) = piecewise linear surface computed from p
         where x is normalized by mean 0.5 and std 0.2745
         and where y is normalized by mean 227.7 and std 80.16
       Coefficients:
           p = coefficient structure
>> class(c)
ans =
sfit
>> coeffvalues(c)
    ans = 
    TriangleSurfaceInterpolant with properties:
      Type: 'Linear'
>> c.p
ans = 
    TriangleSurfaceInterpolant with properties:
      Type: 'Linear'
>> c(0.3, 201)
ans =
          26349

Is it possible to get coefficient of

c() function?

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Answer 1

Greig 2015-3-3

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https://ww2.mathworks.cn/matlabcentral/answers/181171-sfit-object-can-t-get-coefficients#answer_169907

As Sean de Wolski points out in the question that you linked to, a interpolated surface fit has multiple sets of linear fit coefficients, one for each point in the data.

If you want to have just a single set of coefficients for the entire surface fit you will need to use a polynomial fit. For example, if you want to use a 2nd order polynomial in both x and z, set the fittype to 'poly22'. The c.p00, c.p10, c.p01, c.p11, c.p20, c.p02 will contain all of your coefficients.

If this is not what you are looking for could you gives us some more details about what your are wanting.