Help!!! Least square fitting

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Moza Salem
Moza Salem 2021-3-20
编辑： Moza Salem 2021-3-20
I have a set of values P and D :
P = [175.2582 150.9053 103.9622 69.9965 48.6696]
D = [0 31.3300 61.3200 91.3800 121.4000]
and i want to use the following equation to find a and b
D = a * (P- b)^2
but I have to satisfy the following conditions
if P <= b then D=a * (P- b)^2
else D=0
How can i do this and fit the data?

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Matt J
Matt J 2021-3-20
编辑：Matt J 2021-3-20
Ran in:
Using fminspleas from the File Exchange,
P = flip([175.2582 150.9053 103.9622 69.9965 48.6696]).';
D = flip([0 31.3300 61.3200 91.3800 121.4000]).';
funlist={@(b,P) (P<=b).*(P-b).^2};
[b,a]=fminspleas(funlist,P(end), P,D),
b = 230.0623
a = 0.0037
fn=@(P) a*funlist{1}(b,P); %fitted function
plot(P,D,'x',P,fn(P));
  1 个评论
Moza Salem
Moza Salem 2021-3-20
编辑：Moza Salem 2021-3-20
Thank you very much !!! without your help I wouldn't be able to get my beam imprint

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