The WolfeLS class performs an inexact line search on 'f' to find a point 'x' that exhibits (1) sufficient decrease ('f(x)' enough less that 'f(0)') and (2) the slope at x is less steep than the slope at 0. That is, the line search looks for a value for 'x' satisfying the two Wolfe conditions.

f(x) <= f(0) + c1 * f'(0) * x Wolfe condition 1 (Armijo condition) |f'(x)| <= |c2 * f'(0)| Wolfe condition 2 (Strong version) f'(x) >= c2 * f'(0) Wolfe condition 2 (Weak version, more robust)

It works on scalar functions (@see WolfeLSTest). If starting with a vector function f(x), simply define a new function g(y) = x0 + direction * y (@see WolfeLSTest2).