Polyval input when manual value

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Benjamin 2015-1-5

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https://ww2.mathworks.cn/matlabcentral/answers/168970-polyval-input-when-manual-value

编辑： dpb 2015-1-5

Hi, I create a first 3*5 matrix using polyfit() corresponding to 3 curves

for xx=1:length(pix_x)
     y=BrightTN(:,pixels(xx));
     p=polyfit(x,y,4);
     P(xx,:)=p(1,:);
     y1= polyval(p,x);
     plot(x,y1,Color(xx))
end

When using polyval() on these, everything fine, i get value between 0 and 1.

R=zeros(134,3);x=sigma;
R(:,1)= polyval(P(1,:),x);
R(:,2)= polyval(P(2,:),x);
R(:,3)= polyval(P(3,:),x);

If a create a matrix by manually entering same value , polyval() return bad value between -38 and 64, i don't understand why.

P2=[-1.9563e-10    8.8342e-7     -0.0015    1.0858   -296.2330;
     4.8228e-10   -2.0601e-6      0.0033   -2.2701    585.5897;
    -3.7439e-10    1.7088e-6     -0.0029    2.1705   -602.1542;];