import tensorflow as tf

        self.IRK_beta = weights[-1:,:]        
        self.IRK_times = tmp[q**2+q:]
        
        # tf placeholders and graph
        self.sess = tf.Session(config=tf.ConfigProto(allow_soft_placement=True,
                                                     log_device_placement=True))
        
        self.x0_tf = tf.placeholder(tf.float32, shape=(None, self.x0.shape[1]))
