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A universal function (or ufunc for short) is a function that operates on ndarrays in an element-by-element fashion, supporting array broadcasting, type casting, and several other standard features.
Python for Data Analysis Second Edition
https://docs.scipy.org/doc/numpy/reference/ufuncs.html#methods
原文：https://www.cnblogs.com/agilestyle/p/12247644.html