numpy.linspace(start, stop, num=50, endpoint=True, retstep=False, dtype=None)
产生从start到stop的等差数列，num为元素个数，默认50个
多用于模型训练
>>>numpy.linspace(1,10)
#out:
>[ 1. 1.18367347 1.36734694 1.55102041 1.73469388
1.91836735 2.10204082 2.28571429 2.46938776 2.65306122
2.83673469 3.02040816 3.20408163 3.3877551 3.57142857
3.75510204 3.93877551 4.12244898 4.30612245 4.48979592
4.67346939 4.85714286 5.04081633 5.2244898 5.40816327
5.59183673 5.7755102 5.95918367 6.14285714 6.32653061
6.51020408 6.69387755 6.87755102 7.06122449 7.24489796
7.42857143 7.6122449 7.79591837 7.97959184 8.16326531
8.34693878 8.53061224 8.71428571 8.89795918 9.08163265
9.26530612 9.44897959 9.63265306 9.81632653 10. ]
