不知道为啥溢出了
python linear_demo2.py [[ 1.95] [ 0.65] [ 0.7 ] [-0.55]] /home/lbx/.local/lib/python2.7/site-packages/numpy/core/_methods.py:32: RuntimeWarning: overflow encountered in reduce return umr_sum(a, axis, dtype, out, keepdims) [[nan] [nan] [nan] [nan]]