inp1=tf.placeholder(tf.float32)
inp2=tf.placeholder(tf.float32)
outp3=tf.multiply(inp1,inp2)

with tf.Session() as sess:
    #sess.run(ini)
    #res=sess.run([mul,add])
    print(sess.run(outp3,feed_dict={inp1:[8.1,],inp2:[2,]}))