How to fit curve using 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])

Answer 1

[Star Strider]

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.