用 np.logspace() 创建等比数列

np.logspace( start, stop, num=50, endpoint=True, base=10.0, dtype=None, axis=0, )

Docstring:

　　Return numbers spaced evenly on a log scale.

　　In linear space, the sequence starts at ``base ** start`` (`base` to the power of `start`) and ends with ``base ** stop``

(see `endpoint` below).

 

等比数列通项为：a_n  = a₁ * q^n-1

来源：https://www.cnblogs.com/shanger/p/12043959.html