||This implements the steepest descent line search using the first order expansion of the Taylor's series.
||The Gauss-Newton method is a steepest descent method to minimize a real vector function in the form:
f(x) = [f_1(x), f_2(x), ..., f_m(x)]'
The objective function is
F(x) = f' %*% f
||The Newton-Raphson method is a second order steepest descent method that is based on
the quadratic approximation of the Taylor series.
||A steepest descent algorithm finds the minimum by moving along the negative of the steepest gradient direction.