It is, however polyfit wil not do it for you.
Try this:
x = 1:10; % Create ‘x’
y = randn(size(x)) + 0.2*x; % Create ‘y’
linearCoefficients = polyfit(x, y, 1); % Coefficients
yfit = polyval(linearCoefficients, x); % Estimated Regression Line
SStot = sum((y-mean(y)).^2); % Total Sum-Of-Squares
SSres = sum((y-yfit).^2); % Residual Sum-Of-Squares
Rsq = 1-SSres/SStot; % R^2
