lsqcurvefit with two functions and same vriables

Question

Yama Abawi 2021-4-22

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/809900-lsqcurvefit-with-two-functions-and-same-vriables

评论： Hung Huu Vo 2022-11-22

采纳的回答： Matt J

在 MATLAB Online 中打开

Hi, this is my problem:

I have two data sets X1,Y1 and X1,Y2. For exmaple

X1 =

0.0079

0.0157

0.0314

0.0629

Y1 =

2.5172

3.0338

2.5687

2.2744

Y2 =

0.3167

0.7461

0.3454

0.3072

Now the data set X1,Y1 has to be fitted with the function fun_1 and the data set X1,Y2 with the function fun_2 using lsqcurvefit.

This is my code, which is NOT working:

% Putting both data sets in one vector for X and one vector for Y:
         XX = [X1;X1]
         YY = [Y1;Y1]
  
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  Start and boundary data
    %%%-----Parameter(1):
    start_p1=10;
    lb_p1=0;
    ub_p1=100;
   
    %%%-----Parameter(2):
    start_p2=-0.5;
    lb_p2=-1;
    ub_p2=0;    
   
    parameterstart = [start_p1,start_p2];
    lb =[lb_p1,lb_p2];
    ub =[ub_p1,ub_p2];        
% Declaration of the functions
       fun_1 = @(parameter,x)parameter(1).*(x).^parameter(2);    
       fun_2 = @(parameter,x)(-parameter(1).*cot(((parameter(2)+1)*pi)/2)).*(x).^parameter(2);    
% Putting both functions in one array     
       fun_12=@(parameter,x)[fun_1(parameter,x), fun_2(parameter,x)];    
% Fitting with lsqcurvefit      
       parameter = lsqcurvefit(fun_12,parameterstart,XX,YY,lb,ub)
       
    

The error is

Error using lsqcurvefit (line 262)

Function value and YDATA sizes are not equal

The problem is that XX has the dimension 8x1, but since XX is addressed by fun_12 twice (since it contains two functions fun_1 and fun_2) , fun_12 becomes the dimension 8x2.

How can this problem be solved?

Thanks in Advance :-)

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Hung Huu Vo 2022-11-22

Thank you very much for your super helpful question

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Answer 1

Matt J 2021-4-22

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/809900-lsqcurvefit-with-two-functions-and-same-vriables#answer_681825

No, the problem is that YY is not 8x2.

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Yama Abawi 2021-4-22

:-)

Thanka alot Matt J for the quick response. It helped. I adapted YY and now I dont get the error message, but I need to check if the results are reasonable.

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