#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
Task for Branin Function
=========================
"""
import copy
import math
import numpy
from orion.benchmark.task.base import BaseTask
[docs]class Branin(BaseTask):
"""`Branin function <http://infinity77.net/global_optimization/test_functions_nd_B.html#go_benchmark.Branin01>`_
as benchmark task
"""
def __init__(self, max_trials=20):
super(Branin, self).__init__(max_trials=max_trials)
[docs] def call(self, x):
"""Evaluate a 2-D branin function."""
x = copy.deepcopy(x)
x[0] = (x[0] * 15) - 5
x[1] = x[1] * 15
a = 1
b = 5.1 / (4 * numpy.square(math.pi))
c = 5 / math.pi
r = 6
t = 1 / (8 * math.pi)
s = 10
y = (
a * numpy.square(x[1] - b * numpy.square(x[0]) + c * x[0] - r)
+ s * (1 - t) * numpy.cos(x[0])
+ s
)
return [dict(name="branin", type="objective", value=y)]
[docs] def get_search_space(self):
"""Return the search space for the task objective function"""
rspace = {"x": "uniform(0, 1, shape=2, precision=10)"}
return rspace