There is an error of the example Andrew used here to demonstrate Normal equation. The X is the 4 by 5 matrix which makes the system underdetermined, which also result in the inverse of X's transpose multiplying X having no inverse. So the Normal equation cannot be calculable.
There is an error of the example Andrew used here to demonstrate Normal equation. The X is the 4 by 5 matrix which makes the system underdetermined, which also result in the inverse of X's transpose multiplying X having no inverse. So the Normal equation cannot be calculable.
X is 4x5 and X(transpose) is 5x4. Therefore, X(transpose)*X = 5x4 * 4x5 which results in a 5x5 matrix, which has an inverse.
@@bonipomei Very late reply but being a square matrix doesn't mean it has inverse.
@@brownishcookie yes especially if its determinant is 0