Source code for gemseo.problems.uncertainty.ishigami.functions

# Copyright 2021 IRT Saint Exupéry, https://www.irt-saintexupery.com
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License version 3 as published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program; if not, write to the Free Software Foundation,
# Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
"""The Ishigami function and its gradient."""

from __future__ import annotations

from typing import TYPE_CHECKING

from numpy import atleast_1d
from numpy import cos
from numpy import sin

if TYPE_CHECKING:
    from gemseo.typing import RealArray




def compute_output(x: RealArray) -> float | RealArray:
    """Compute the output of the Ishigami function.

    Args:
        x: The input value(s),
           shaped as ``(input_dimension,)`` or ``(n_values, input_dimension)``.

    Returns:
        The output value(s),
        either a float or an array shaped as ``(n_values,)``.
    """
    return sin(x[..., 0]) * (1 + 0.1 * x[..., 2] ** 4) + 7 * sin(x[..., 1]) ** 2





def compute_gradient(x: RealArray) -> RealArray:
    """Compute the gradient of the Ishigami function.

    Args:
        x: The input value(s),
           shaped as ``(input_dimension,)`` or ``(n_values, input_dimension)``.

    Returns:
        The value(s) of the gradient of the Ishigami function,
        shaped as ``(input_dimension,)`` or ``(n_values, input_dimension)``.
    """
    result = atleast_1d([
        cos(x[..., 0]) * (1 + 0.1 * x[..., 2] ** 4),
        14 * sin(x[..., 1]) * cos(x[..., 1]),
        0.4 * sin(x[..., 0]) * x[..., 2] ** 3,
    ])
    if result.ndim == 2:
        return result.T

    return result