pub fn branin(x: &[f64]) -> f64Expand description
Branin’s function of two variables, x₀ in [−5, 10] and x₁ in [0, 15]:
f = (x₁ − b x₀² + c x₀ − r)² + s (1 − t) cos x₀ + s, with b = 5.1/(4π²), c = 5/π,
r = 6, s = 10 and t = 1/(8π).