# Newton Raphson Method with Line Search

1. Jul 10, 2013

### brunnels

I am developing a code that uses Newton's method to optimize a functional W:ℝ6→ℝ
Because the functional is poorly represented by a quadratic, convergence is slow. Therefore I've implemented a line search using two methods: the secant method and the backtracking method (with the Armijo condition)
My problem is that the line search produces a factor of zero. When plotting
W(x + α Δx) $\ \ \ \ \$ α$\in$[-1,1]
as a function of $\alpha$, it is clear that α=0 is a minimizer. I can't understand why this would be the case.