How to use lsqcurvefit to find constant values?

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R7 DR 2015-3-16

评论： Star Strider 2015-3-16

How to use 'lsqcurvefit' to find the coefficient values 'a' and 'b'.

The blue line(A1) is produced from the experimental data and the green line is based on the 'nlinfit' function. But the error is very high.

Is it possible to use 'lsqcurvefit' and find the constant values?

A1=[......] % experimental data

A2= a*exp(b/X)*Y %function for greenline.

X=[.........] Y=[.........] I know the values of X and Y.

The ultimate aim is to reduce the error and finding the best fitted constant values.

Thanks

Star Strider 2015-3-16

编辑：Star Strider 2015-3-16

You have to create a single matrix of your ‘X’ and ‘Y’ values:

XY = [X(:) Y(:)];

Then create your objective function ‘A2’ as:

% b(1) = a,  b(2) = b
A2 = @(b, XY) b(1) .* exp(b(2)./XY(:,1)) .* XY(:,2);

And give it to lsqcurvefit as:

B0 = randi(10, 2, 1);       % Choose Appropriate Initial Parameter Estimates
B = lsqcurvefit(A2, B0, XY, A1);

Where ‘B(1)=a’ and ‘B(2)=b’.

R7 DR 2015-3-16

thanks for your help.

I will check my model.

Star Strider 2015-3-16

My pleasure.

I get a significantly different plot from the figure you posted. What data did you use to create it?

What figure do you get when you use my code?

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