问题描述
我正在尝试理解 D 语言运行时中的一些代码.似乎以下两件事有单独的功能:
I'm trying to understand some code in the D language runtime. It seems like there are separate functions for the following two things:
array1[] += scalar * array2[];
array1[] += array2[] * scalar;
为什么不能用一个函数来完成这些?我认为即使在不精确的浮点运算中，乘法也是可交换的.
Why can't these be done with one function? I thought multiplication was commutative even in inexact floating-point arithmetic.
推荐答案
我对 D 语言一无所知，但我很乐意回答你标题中的问题:
I know nothing about the D language, but I'll happily answer the question in your title:
在不精确的浮点运算中，乘法总是可交换的吗?
直到 NaN 值的有效载荷"，是的.IEEE-754 浮点乘法是可交换的(加法也是如此).如果您不知道 NaN 的有效载荷是什么，请不要担心.
Up to the "payload" of NaN values, yes. IEEE-754 floating-point multiplication is commutative (and so is addition). If you don't know what the payload of a NaN is, don't worry about it.
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