Problem with non-linear fit
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Hi I am trying to fit the data and find the constant values. my code is...
[T]=xlsread('Matlab.xlsx','sheet2','C5:C2685')
[alpha]=xlsread('Matlab.xlsx','sheet2','I5:I2685')%time
[dalpha_dt]=xlsread('Matlab.xlsx','sheet2','J5:J2685')
F=ones(size(alpha));
F=(1-alpha)
coeff0=[2.17E+22, 5] % initial guess
coeff=nlinfit([T,F],dalpha_dt,@model,coeff0);
A=coeff(:,1)
n=coeff(:,2)
Function:
function dhat=model(coef,a)
% par_fit = [a b]
a=coef(1);
b=coef(2);
T=a(:,1);
F=a(:,2);
% predicted model
dhat=a.*exp(208000./(8.3147*(T+273))).*(F^b);
return
I need to find the new coefficient values, but it is showing following error..Please tell me how to resolve this.
Error using nlinfit (line 205)
Error evaluating model function 'model'.
Error in fitting (line 16)
coeff=nlinfit([T,F],dalpha_dt,@model,coeff0);
Caused by:
Attempted to access a(:,2); index out of bounds because numel(a)=1.
Thanks
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回答 (2 件)
Star Strider
2015 年 10 月 9 日
You defined ‘a’ as a scalar (appropriately) so it is by definition a (1x1) ‘array’ (taking liberties with the concept here). It doesn’t have a second dimension.
How do you want to define ‘T’ and ‘F’?
11 件のコメント
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