`scipy.optimize._optimize:_linesearch_powell`

Signature

def _linesearch_powell(func, p, xi, tol = 0.001, lower_bound = None, upper_bound = None, fval = None)

Line-search algorithm using fminbound.

Find the minimum of the function func(x0 + alpha*direc).

lower_bound: The lower bounds for each parameter in x0. If the i``th parameter in ``x0 is unbounded below, then lower_bound[i] should be -np.inf. Note np.shape(lower_bound) == (n,).
upper_bound: The upper bounds for each parameter in x0. If the i``th parameter in ``x0 is unbounded above, then upper_bound[i] should be np.inf. Note np.shape(upper_bound) == (n,).
fval: fval is equal to func(p), the idea is just to avoid recomputing it so we can limit the fevals.