1 // Copyright 2010 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package math 6 7 // Dim returns the maximum of x-y or 0. 8 // 9 // Special cases are: 10 // Dim(+Inf, +Inf) = NaN 11 // Dim(-Inf, -Inf) = NaN 12 // Dim(x, NaN) = Dim(NaN, x) = NaN 13 func Dim(x, y float64) float64 { 14 // The special cases result in NaN after the subtraction: 15 // +Inf - +Inf = NaN 16 // -Inf - -Inf = NaN 17 // NaN - y = NaN 18 // x - NaN = NaN 19 v := x - y 20 if v <= 0 { 21 // v is negative or 0 22 return 0 23 } 24 // v is positive or NaN 25 return v 26 } 27 28 // Max returns the larger of x or y. 29 // 30 // Special cases are: 31 // Max(x, +Inf) = Max(+Inf, x) = +Inf 32 // Max(x, NaN) = Max(NaN, x) = NaN 33 // Max(+0, 0) = Max(0, +0) = +0 34 // Max(-0, -0) = -0 35 func Max(x, y float64) float64 36 37 func max(x, y float64) float64 { 38 // special cases 39 switch { 40 case IsInf(x, 1) || IsInf(y, 1): 41 return Inf(1) 42 case IsNaN(x) || IsNaN(y): 43 return NaN() 44 case x == 0 && x == y: 45 if Signbit(x) { 46 return y 47 } 48 return x 49 } 50 if x > y { 51 return x 52 } 53 return y 54 } 55 56 // Min returns the smaller of x or y. 57 // 58 // Special cases are: 59 // Min(x, -Inf) = Min(-Inf, x) = -Inf 60 // Min(x, NaN) = Min(NaN, x) = NaN 61 // Min(-0, 0) = Min(0, -0) = -0 62 func Min(x, y float64) float64 63 64 func min(x, y float64) float64 { 65 // special cases 66 switch { 67 case IsInf(x, -1) || IsInf(y, -1): 68 return Inf(-1) 69 case IsNaN(x) || IsNaN(y): 70 return NaN() 71 case x == 0 && x == y: 72 if Signbit(x) { 73 return x 74 } 75 return y 76 } 77 if x < y { 78 return x 79 } 80 return y 81 } 82
