math: update special-conditions comments to use ± symbol

R=rsc, golang-dev, r
CC=golang-dev
https://golang.org/cl/5445046

src/pkg/math/abs.go

@@ -7,8 +7,7 @@ package math
 // Abs returns the absolute value of x.
 //
 // Special cases are:
-//	Abs(+Inf) = +Inf
+//	Abs(±Inf) = +Inf
-//	Abs(-Inf) = +Inf
 //	Abs(NaN) = NaN
 func Abs(x float64) float64 {
 	switch {

src/pkg/math/asinh.go

@@ -33,8 +33,7 @@ package math
 // Asinh(x) calculates the inverse hyperbolic sine of x.
 //
 // Special cases are:
-//	Asinh(+Inf) = +Inf
+//	Asinh(±Inf) = ±Inf
-//	Asinh(-Inf) = -Inf
 //	Asinh(NaN) = NaN
 func Asinh(x float64) float64 {
 	const (

src/pkg/math/floor.go

@@ -7,8 +7,7 @@ package math
 // Floor returns the greatest integer value less than or equal to x.
 //
 // Special cases are:
-//	Floor(+Inf) = +Inf
+//	Floor(±Inf) = ±Inf
-//	Floor(-Inf) = -Inf
 //	Floor(NaN) = NaN
 func Floor(x float64) float64 {
 	// TODO(rsc): Remove manual inlining of IsNaN, IsInf
@@ -30,16 +29,14 @@ func Floor(x float64) float64 {
 // Ceil returns the least integer value greater than or equal to x.
 //
 // Special cases are:
-//	Ceil(+Inf) = +Inf
+//	Ceil(±Inf) = ±Inf
-//	Ceil(-Inf) = -Inf
 //	Ceil(NaN) = NaN
 func Ceil(x float64) float64 { return -Floor(-x) }
 
 // Trunc returns the integer value of x.
 //
 // Special cases are:
-//	Trunc(+Inf) = +Inf
+//	Trunc(±Inf) = ±Inf
-//	Trunc(-Inf) = -Inf
 //	Trunc(NaN) = NaN
 func Trunc(x float64) float64 {
 	// TODO(rsc): Remove manual inlining of IsNaN, IsInf

src/pkg/math/gamma.go

@@ -113,8 +113,7 @@ func stirling(x float64) float64 {
 // Gamma(x) returns the Gamma function of x.
 //
 // Special cases are:
-//	Gamma(Inf) = Inf
+//	Gamma(±Inf) = ±Inf
-//	Gamma(-Inf) = -Inf
 //	Gamma(NaN) = NaN
 // Large values overflow to +Inf.
 // Negative integer values equal ±Inf.

src/pkg/math/modf.go

@@ -8,8 +8,7 @@ package math
 // that sum to f.  Both values have the same sign as f.
 //
 // Special cases are:
-//	Modf(+Inf) = +Inf, NaN
+//	Modf(±Inf) = ±Inf, NaN
-//	Modf(-Inf) = -Inf, NaN
 //	Modf(NaN) = NaN, NaN
 func Modf(f float64) (int float64, frac float64) {
 	if f < 1 {

src/pkg/math/sincos.go

@@ -7,7 +7,6 @@ package math
 // Sincos(x) returns Sin(x), Cos(x).
 //
 // Special conditions are:
-//	Sincos(+Inf) = NaN, NaN
+//	Sincos(±Inf) = NaN, NaN
-//	Sincos(-Inf) = NaN, NaN
 //	Sincos(NaN) = NaN, NaN
 func Sincos(x float64) (sin, cos float64) { return Sin(x), Cos(x) }