dot函数

dot函数是两个向量的点乘，注意lua中dot函数的写法

th> a
 1  2  3
[torch.DoubleTensor of size 1x3]

                                                                      [0.0002s]
th> b
 1  2  0
[torch.DoubleTensor of size 1x3]

                                                                      [0.0002s]
th> c=a:dot(b)
                                                                      [0.0001s]
th> c
5