通过忽略golang中的最后一位来比较浮点数

Question

A specification reads as follows:

It still considers real numbers equal if they differ in their last binary digit.

I would like to implement this way of comparing floats for the float64 data type in Go. Unfortunately, the bitwise operators aren't defined for floating point numbers. Is there a way to achieve this way of comparing floats in the Go language?

Answer 1

If you want to know if two float64 values are adjacent (that is, there's no float64 value between them):

func almostEqual(a, b float64) bool {
    ai, bi := int64(math.Float64bits(a)), int64(math.Float64bits(b))
    return a == b || -1 <= ai-bi && ai-bi <= 1
}

Mostly that's the same as saying they differ in the lowest bit of their mantissa.

This code doesn't work if a or b are NaNs, zeros or infinities, but you could add special cases if you wished.

See https://randomascii.wordpress.com/2012/01/23/stupid-float-tricks-2/