import numpy as np
from iOpt.trial import Point
from iOpt.trial import FunctionValue
from iOpt.trial import Trial
from iOpt.problem import Problem
import math
[документация]class Rastrigin(Problem):
"""
The Rastrigin function is given by the formula:
:math:`f(y)=(\sum_{i=1}^{N}[x_{i}^{2}-10*cos(2\pi x_{i})])`,
where :math:`x\in [-2.2, 1.8], N` – problem dimensionality
"""
[документация] def __init__(self, dimension: int):
"""
The constructor of the Rastrigin problem class
:param dimension: problem dimensionality.
"""
super(Rastrigin, self).__init__()
self.name = "Rastrigin"
self.dimension = dimension
self.number_of_float_variables = dimension
self.number_of_discrete_variables = 0
self.number_of_objectives = 1
self.number_of_constraints = 0
self.float_variable_names = np.ndarray(shape=(self.dimension), dtype=str)
for i in range(self.dimension):
self.float_variable_names[i] = i
self.lower_bound_of_float_variables = np.ndarray(shape=(self.dimension), dtype=np.double)
self.lower_bound_of_float_variables.fill(-2.2)
self.upper_bound_of_float_variables = np.ndarray(shape=(self.dimension), dtype=np.double)
self.upper_bound_of_float_variables.fill(1.8)
self.known_optimum = np.ndarray(shape=(1), dtype=Trial)
pointfv = np.ndarray(shape=(self.dimension), dtype=np.double)
pointfv.fill(0)
KOpoint = Point(pointfv, [])
KOfunV = np.ndarray(shape=(1), dtype=FunctionValue)
KOfunV[0] = FunctionValue()
KOfunV[0].value = 0
self.known_optimum[0] = Trial(KOpoint, KOfunV)
[документация] def calculate(self, point: Point, function_value: FunctionValue) -> FunctionValue:
"""
Calculate the value of the selected function at a given point
:param point: coordinates of the trial point where the value of the function will be calculated.
:param function_value: object defining the function number in the task and storing the function value.
:return: Calculated value of the function at point.
"""
sum: np.double = 0
for i in range(self.dimension):
sum += point.float_variables[i] * point.float_variables[i] - 10 * math.cos(
2 * math.pi * point.float_variables[i]) + 10
function_value.value = sum
return function_value