Go で浮動小数点数を正確かつ効率的に比較するにはどうすればよいですか?

func Equal(a, b float64) bool {
    ba := math.Float64bits(a)
    bb := math.Float64bits(b)
    diff := ba - bb
    if diff < 0 {
        diff = -diff
    }
    // accept one bit difference
    return diff < 2
}

package main

import (
    "fmt"
    "math"
)

const float64EqualityThreshold = 1e-9

func almostEqual(a, b float64) bool {
    return math.Abs(a - b) <= float64EqualityThreshold
}

func main() {
    a := 0.1
    b := 0.2
    fmt.Println(almostEqual(a + b, 0.3))
}