how to calculate optimal value of a unknown constant of an equation with known data points?

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pooja sudha 2020-9-10

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https://ww2.mathworks.cn/matlabcentral/answers/591871-how-to-calculate-optimal-value-of-a-unknown-constant-of-an-equation-with-known-data-points

评论： pooja sudha 2020-9-11

采纳的回答： Walter Roberson

Hey, I wanted to solve for the optimal value of constant. I have data points of the equation .

please help, how can I do that.

equation is:

y= 1/sqrt(k^2+x^2)

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Walter Roberson 2020-9-11

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https://ww2.mathworks.cn/matlabcentral/answers/591871-how-to-calculate-optimal-value-of-a-unknown-constant-of-an-equation-with-known-data-points#answer_492934

在 MATLAB Online 中打开

k0 = rand() * 10;
bestk = lsqcurvefit( @(k,x)1./sqrt(k.^2+x.^2), k0, x, y);

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Adam Danz 2020-9-11

We don't know what to do either without knowing the full error message :)

If you're looking for an optimal k, Walter's approach is probably the one you want to pursue. If you have questions about your results, we need the inputs you're using so we can reproduce the results.

pooja sudha 2020-9-11

Hey Thanks Adam and Walter , I found the result :)

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Adam Danz 2020-9-10

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k = sqrt((1/y)^2 - x^2)

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Walter Roberson 2020-9-11

在 MATLAB Online 中打开

k = mean(sqrt((1/y)^2 - x^2));

Adam Danz 2020-9-11

在 MATLAB Online 中打开

% assign demo values
k = 2.2;                   % = 2.2
x = 1:10;                  % = [1,2,3,4,5,6,7,8,9,10]
y = 1./sqrt(k^2 + x.^2);   % = [0.41 0.33 0.26 0.21 0.18 0.15 0.13 0.12 0.10 0.09]
% Solve for k
k = sqrt((1./y).^2 - x.^2) % = [2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 ]
k = sqrt((1/y(1))^2 - x(1)^2) % = 2.2