cmp/cmpopts/equate.go
func EquateApprox(fraction, margin float64) cmp.Option {
	if margin < 0 || fraction < 0 || math.IsNaN(margin) || math.IsNaN(fraction) {
		panic("margin or fraction must be a non-negative number")
	}
	a := approximator{fraction, margin}
	return cmp.Options{
		cmp.FilterValues(areRealF64s, cmp.Comparer(a.compareF64)),
		cmp.FilterValues(areRealF32s, cmp.Comparer(a.compareF32)),
	}
}
func EquateApprox(fraction, margin float64) cmp.Option {
	if margin < 0 || fraction < 0 || math.IsNaN(margin) || math.IsNaN(fraction) {
		panic("margin or fraction must be a non-negative number")
	}
	a := approximator{fraction, margin}
	return cmp.Options{
		cmp.FilterValues(areRealF64s, cmp.Comparer(a.compareF64)),
		cmp.FilterValues(areRealF32s, cmp.Comparer(a.compareF32)),
	}
}
// EquateApprox returns a Comparer option that determines float32 or float64
// values to be equal if they are within a relative fraction or absolute margin.
// This option is not used when either x or y is NaN or infinite.
//
// The fraction determines that the difference of two values must be within the
// smaller fraction of the two values, while the margin determines that the two
// values must be within some absolute margin.
// To express only a fraction or only a margin, use 0 for the other parameter.
// The fraction and margin must be non-negative.
//
// The mathematical expression used is equivalent to:
//	|x-y| ≤ max(fraction*min(|x|, |y|), margin)
//
// EquateApprox can be used in conjunction with EquateNaNs.