How can I find the coefficient of my function by using regression in matlab?

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Parham Babakhani Dehkordi 2015-3-23

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评论： John D'Errico 2015-3-23

Hi, I really in trouble to find the coefficients of my function as follows: f=A+B(h/D)^n;

f=[6.67836E-05 3.6796E-05 2.30952E-05 1.51082E-05 1.05262E-05 7.56192E-06 5.54116E-06 3.096E-06]; h/D=[0.7696 0.8079 0.8327 0.8523 0.8669 0.8790 0.8892 0.9060];

I need to find the values of coefficients A, B and n by regression, however, I would not be able to do that. any help would be appreciated. Thanks in advance

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Answer 1

John D'Errico 2015-3-23

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编辑：John D'Errico 2015-3-23

在 MATLAB Online 中打开

Easy enough.

f=[6.67836E-05 3.6796E-05 2.30952E-05 1.51082E-05 1.05262E-05 7.56192E-06 5.54116E-06 3.096E-06];
hd=[0.7696 0.8079 0.8327 0.8523 0.8669 0.8790 0.8892 0.9060];

Using my fminspleas tool, downloaded from the FEX...

funs = {1,@(c,x) x.^c};
[INLP,ILP] = fminspleas(funs,-2,hd,f)
INLP =
      -10.064
ILP =
  -1.3159e-05
   5.7457e-06
n = INLP;
A = ILP(1);
B = ILP(2);

The curve fitting toolbox would do it quite simply too.

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Parham Babakhani Dehkordi 2015-3-23

Thank you John for you response,I am beginner in matlab. I wrote the code as follows:

f=[6.67836E-05 3.6796E-05 2.30952E-05 1.51082E-05 1.05262E-05 7.56192E-06 5.54116E-06 3.096E-06]; hd=[0.7696 0.8079 0.8327 0.8523 0.8669 0.8790 0.8892 0.9060]; funs = {1,@(c,x) x.^c}; [INLP,ILP] = fminspleas(funs,-2,hd,f) n = INLP; A = ILP(1); B = ILP(2);

However, there is an error to run the command, 'Undefined function 'fminspleas' for input arguments of type 'cell'.

Error in b (line 4) [INLP,ILP] = fminspleas(funs,-2,hd,f)

John D'Errico 2015-3-23

I'm quite confident that I told you that you need to download it from the file exchange. Given that I'm looking at my response now as I type this, I can be seriously confident of that fact. In fact, I even gave you a link to do that.

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