# -*- coding: utf-8 -*-

# Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. (MPG) is
# holder of all proprietary rights on this computer program.
# You can only use this computer program if you have closed
# a license agreement with MPG or you get the right to use the computer
# program from someone who is authorized to grant you that right.
# Any use of the computer program without a valid license is prohibited and
# liable to prosecution.
#
# Copyright©2020 Max-Planck-Gesellschaft zur Förderung
# der Wissenschaften e.V. (MPG). acting on behalf of its Max Planck Institute
# for Intelligent Systems. All rights reserved.
#
# Contact: Vassilis Choutas, vassilis.choutas@tuebingen.mpg.de
from __future__ import absolute_import
from __future__ import print_function
from __future__ import division

import numpy as np


def rel_change(prev_val, curr_val):
    return (prev_val - curr_val) / max([np.abs(prev_val), np.abs(curr_val), 1])


def max_grad_change(grad_arr):
    return grad_arr.abs().max()


def to_np(array, dtype=np.float32):
    if hasattr(array, 'todense'):
        array = array.todense()
    return np.array(array, dtype=dtype)