How to fit linear plateau equation ?

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madhuri dubey 2018-12-8

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评论： Bruno Luong 2018-12-10

采纳的回答： Bruno Luong

I want to fit linear equation with plateau condition.

y=a(x+n)+b

These are the data in which I Want to fit:

x=[0,80,100,120,150],

y=[1865,3608,4057,4343,4389]

I don not know how to find the plateau value of yield.

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madhuri dubey 2018-12-8

Ok the another data data set is

x= x=[0,40,80,100,120,150,170,200],

y=[1865,2855,3608,4057,4343,4389,4415,4478]

I don't know how to fit plateau condition in linear equation that is why i asked to help. The plateau condition are given here;

x < xc(Ymax) ;

y=yp, x >= xc(Ymax)

John D'Errico 2018-12-10

I give up.

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Bruno Luong 2018-12-10

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https://ww2.mathworks.cn/matlabcentral/answers/434616-how-to-fit-linear-plateau-equation#answer_351549

编辑：Bruno Luong 2018-12-10

在 MATLAB Online 中打开

You can use this FEX file (BSFK)

The code is by default use QUADPROG from MATLAB, but can also work with QPAS project by Adrian Wills for user who has not access to optimization toolbox as showed below:

x=[0,40,80,100,120,150,170,200];
y=[1865,2855,3608,4057,4343,4389,4415,4478];
opt = struct('KnotRemoval','none','sigma',1,'qpengine','qpas');
pp = BSFK(x,y,2,2,[],opt);
% prepare graphical data
xi = linspace(min(x),max(x));
yi = ppval(pp,xi);
xb = pp.breaks(2);
yb = ppval(pp,xb);
clf
plot(x,y,'or',xi,yi,'-b');
xline(pp.breaks(2));
text(xb,yb,sprintf('(%g,%g)',xb,yb));