python numpy机器epsilon [英] python numpy machine epsilon

问题描述

我试图了解什么是机器epsilon.根据Wikipedia，其计算公式如下:

I am trying to understand what is machine epsilon. According to the Wikipedia, it can be calculated as follows:

def machineEpsilon(func=float):
    machine_epsilon = func(1)
    while func(1)+func(machine_epsilon) != func(1):
        machine_epsilon_last = machine_epsilon
        machine_epsilon = func(machine_epsilon) / func(2)
    return machine_epsilon_last

但是，它仅适用于双精度数字.我有兴趣修改它以支持单精度数字.我读到可以使用numpy，尤其是numpy.float32类.有人可以帮助您修改功能吗?

However, it is suitable only for double precision numbers. I am interested in modifying it to support also single precision numbers. I read that numpy can be used, particularly numpy.float32 class. Can anybody help with modifying the function?

推荐答案

获取给定浮点类型的机器epsilon的更简单方法是使用

An easier way to get the machine epsilon for a given float type is to use np.finfo():

print(np.finfo(float).eps)
# 2.22044604925e-16

print(np.finfo(np.float32).eps)
# 1.19209e-07

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