From 7b768d43d0f0e3e734369496bb1caa409d4bd0bb Mon Sep 17 00:00:00 2001 From: Robert Griesemer Date: Fri, 30 Apr 2021 17:23:35 -0700 Subject: [PATCH] math: replace float32/64 extrema with exact expressions Follow-up on https://golang.org/cl/315170. Updates #44057. Updates #44058. Change-Id: I0b071e8ee7a1c97aae2436945cc9583cde3b40b0 Reviewed-on: https://go-review.googlesource.com/c/go/+/315969 Trust: Robert Griesemer Trust: Emmanuel Odeke Reviewed-by: Matthew Dempsky Reviewed-by: Russ Cox --- api/except.txt | 1 + src/math/const.go | 8 ++++---- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/api/except.txt b/api/except.txt index f5a7aa854e..14fe7785fa 100644 --- a/api/except.txt +++ b/api/except.txt @@ -1,5 +1,6 @@ pkg encoding/json, method (*RawMessage) MarshalJSON() ([]uint8, error) pkg math, const MaxFloat64 = 1.79769e+308 // 179769313486231570814527423731704356798100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 +pkg math, const SmallestNonzeroFloat32 = 1.4013e-45 // 17516230804060213386546619791123951641/12500000000000000000000000000000000000000000000000000000000000000000000000000000000 pkg math, const SmallestNonzeroFloat64 = 4.94066e-324 // 4940656458412465441765687928682213723651/1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 pkg math/big, const MaxBase = 36 pkg math/big, type Word uintptr diff --git a/src/math/const.go b/src/math/const.go index 441b295ed4..31954b0cae 100644 --- a/src/math/const.go +++ b/src/math/const.go @@ -28,11 +28,11 @@ const ( // Max is the largest finite value representable by the type. // SmallestNonzero is the smallest positive, non-zero value representable by the type. const ( - MaxFloat32 = 3.40282346638528859811704183484516925440e+38 // 2**127 * (2**24 - 1) / 2**23 - SmallestNonzeroFloat32 = 1.401298464324817070923729583289916131280e-45 // 1 / 2**(127 - 1 + 23) + MaxFloat32 = 0x1p127 * (1 + (1 - 0x1p-23)) // 3.40282346638528859811704183484516925440e+38 + SmallestNonzeroFloat32 = 0x1p-126 * 0x1p-23 // 1.401298464324817070923729583289916131280e-45 - MaxFloat64 = 1.79769313486231570814527423731704356798070e+308 // 2**1023 * (2**53 - 1) / 2**52 - SmallestNonzeroFloat64 = 4.9406564584124654417656879286822137236505980e-324 // 1 / 2**(1023 - 1 + 52) + MaxFloat64 = 0x1p1023 * (1 + (1 - 0x1p-52)) // 1.79769313486231570814527423731704356798070e+308 + SmallestNonzeroFloat64 = 0x1p-1022 * 0x1p-52 // 4.9406564584124654417656879286822137236505980e-324 ) // Integer limit values.