import tensorflow as tf

    target_q_func_vars = tf.get_collection(tf.GraphKeys.GLOBAL_VARIABLES,scope='target_q_func')
    # Bellman training error
    if double_q:
        q_max = gather_2d(q_target,tf.argmax(q_online_tp1,axis=1,output_type=tf.int32))
    else:
        q_max = tf.reduce_max(q_target,axis=1)
