import tensorflow as tf


def delta1(y_true, y_pred):
    max_ratio = tf.maximum(y_pred / y_true, y_true / y_pred)
    return tf.reduce_mean(tf.cast(max_ratio < tf.convert_to_tensor(1.25), tf.float32))


def delta2(y_true, y_pred):
    max_ratio = tf.maximum(y_pred / y_true, y_true / y_pred)
    return tf.reduce_mean(tf.cast(max_ratio < tf.convert_to_tensor(1.25 ** 2), tf.float32))


def delta3(y_true, y_pred):
    max_ratio = tf.maximum(y_pred / y_true, y_true / y_pred)
    return tf.reduce_mean(tf.cast(max_ratio < tf.convert_to_tensor(1.25 ** 3), tf.float32))