How do I use the results of the polyfit command for the rest of my code?

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Nik 2014-7-3

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关闭： MATLAB Answer Bot 2021-8-20

Depending on a single variable 'x', I get a 2nd degree polynomial equation.I needed the values of the coefficients of this polynomial equation. I got those values using the 'polyfit' command. Now i need to use these values in the rest of the procedure. I think this procedure can be automated. How do i use the output of the 'polyfit' command, as input for the rest of the procedure?

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Answer 1

Jos (10584) 2014-7-3

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Useully you would like to use the parameters of the fit to obtained fitted values. Something along these lines, perhaps?

x = 1:10 
y = 2 * x - 8 
ynoise = y + randn(size(y)) % y-values with noise 
p = polyfit(x,ynoise,1) 
yfit = polyval(p,x)  % fitted Y values
plot(x,y,'bo',x,ynoise,'rs', x,yfit,'r.-')
legend({'real','noisy','fitted'})
res = yfit - y % residuals