def inv_scale(x, data_mean, data_std):
    """Inverse tranform of mean/variance scaling.

    Given mean and variances, apply mean-variance denormalization to data.

    Args:
        x (array): Input data
        data_mean (array): Means for each feature dimention.
        data_std (array): Standard deviation for each feature dimention.

    Returns:
        array: Denormalized data.

    See also:
        :func:`nnmnkwii.preprocessing.scale`
    """
    return data_std * x + data_mean
