OLS β = (XᵀX)⁻¹Xᵀy on X=[[1,1],[1,2],[1,3]], y=[1,2,3] ⇒ β=[0,1]

Sympy-exact witness of the OLS normal-equations solution on a perfectly-linear 3-point calibration. Design matrix X (column 1 = intercept, column 2 = abscissa), y aligned with the abscissa, so the exact solution is intercept = 0, slope =…