Python指数运算符和复数 [英] Python exponent operator and complex numbers

问题描述

为什么python为什么 print(type(-1 ** 0.5))返回 float 而不是 complex ?

Why does python does print(type(-1**0.5)) return float instead of complex?

在数学上，始终将float的负整数的平方根视为复数.python指数运算符如何支持获取 complex 数字?

Getting the square root of negative integer of float always mathematically consider as complex numbers. How does python exponent operator support to get complex number?

print(type(-1**0.5))
 <type 'float'>    

推荐答案

在运算的数学顺序中，指数运算先于乘法运算，一元负数作为乘法运算(乘以-1).因此您的表达式与-(1 ** 0.5)相同，其中不包含任何虚数.

In the mathematical order of operations, exponentation comes before multiplication and unary minus counts as multiplication (by -1). So your expression is the same as -(1**0.5), which doesn't involve any imaginary numbers.

如果执行(-1)** 0.5 ，则会在Python 2中出现错误，因为答案不是实数.如果需要复杂的答案，则需要通过执行(-1 + 0j)** 0.5 使用复杂的输入.(在Python 3中，(-1)** 0.5 将返回复杂的结果.)

If you do (-1)**0.5 you'll get an error in Python 2 because the answer isn't a real number. If you want a complex answer, you need to use a complex input by doing (-1+0j)**0.5. (In Python 3, (-1)**0.5 will return a complex result.)

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