Can I apply linear regression to any function to the x's. For example:
Polynomials with one variable: y = w_0 + w_1 * x + w_2 * x2 + ... + w_D * xD
Polynomials with multiple variables (let's say there are 2 variables and the order of the polynomial is also 2, so it's easy to write): y = w_0 + w_1 * x_1 + w_2 * x_2 + w_3 * x_1 * x_2 + w_4 * (x_1)2 + w_5 * (x_2)2
Radial basis functions: y = w_0 + w_1 * f(x_1) + w_2 * f(x_2) + ... + w_D * f(x_D), where f(x) is a radial basis function.