MATLAB: How to fit curve using regress

regress

I'm not sure how regress work we were asked to generate regress function using
this >> Xliner = [X; ones(1,sampleData);];
 but I don't know what does X represent in 
sampleData = 100;
x = linspace(-5,5);
y= 1.6 * x .^2 + 2.5*x+6; 
dataset = randn(2,sampleData); 
figure  
p = polyfit(x,dataset(1,:)+y,1);   
r = p(1) .* x + p(2);  
plot(x,dataset(1,:)+y,'ob','MarkerFaceColor','b')  
hold on
plot(x,dataset(1,:)+y) 
hold off
legend('raw data')
xlim([-4 6])

Best Answer

You would use ‘Xliner’ if you need to do the linear regression using the mldivide function, or ‘\’ operator:
sampleData = 100;
x = linspace(-5,5);
y= 1.6 * x .^2 + 2.5*x+6; 
dataset = randn(2,sampleData);
Xliner = [x; ones(1,sampleData)]';
p = Xliner\[dataset(1,:)+y]';
Notice the transpose (') operator.
It seems you were given incomplete information. See the documentation for mldivide for the details on how it works and how to use it.
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