dim.go

Documentation: math

		 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  	if haveArchMax {
		37  		return archMax(x, y)
		38  	}
		39  	return max(x, y)
		40  }
		41  
		42  func max(x, y float64) float64 {
		43  	// special cases
		44  	switch {
		45  	case IsInf(x, 1) || IsInf(y, 1):
		46  		return Inf(1)
		47  	case IsNaN(x) || IsNaN(y):
		48  		return NaN()
		49  	case x == 0 && x == y:
		50  		if Signbit(x) {
		51  			return y
		52  		}
		53  		return x
		54  	}
		55  	if x > y {
		56  		return x
		57  	}
		58  	return y
		59  }
		60  
		61  // Min returns the smaller of x or y.
		62  //
		63  // Special cases are:
		64  //	Min(x, -Inf) = Min(-Inf, x) = -Inf
		65  //	Min(x, NaN) = Min(NaN, x) = NaN
		66  //	Min(-0, ±0) = Min(±0, -0) = -0
		67  func Min(x, y float64) float64 {
		68  	if haveArchMin {
		69  		return archMin(x, y)
		70  	}
		71  	return min(x, y)
		72  }
		73  
		74  func min(x, y float64) float64 {
		75  	// special cases
		76  	switch {
		77  	case IsInf(x, -1) || IsInf(y, -1):
		78  		return Inf(-1)
		79  	case IsNaN(x) || IsNaN(y):
		80  		return NaN()
		81  	case x == 0 && x == y:
		82  		if Signbit(x) {
		83  			return x
		84  		}
		85  		return y
		86  	}
		87  	if x < y {
		88  		return x
		89  	}
		90  	return y
		91  }
		92
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