import torch


def f_dD(x):
    """Simple example function defined on interval `[0, 1]`

    Parameters
    ----------
    x : torch.Tensor
        coordinates for evaluation

    Returns
    -------
    torch.Tensor
        function evaluations
    """
    result = 4 * x[0] * (x[0] - 1)
    for x_i in x[1:]:
        result *= 4 * x_i * (x_i - 1)
    result *= torch.exp(2 * torch.prod(x, dim=0))
    return result