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 /* 8 Hypot -- sqrt(p*p + q*q), but overflows only if the result does. 9 */ 10 11 // Hypot returns Sqrt(p*p + q*q), taking care to avoid 12 // unnecessary overflow and underflow. 13 // 14 // Special cases are: 15 // Hypot(±Inf, q) = +Inf 16 // Hypot(p, ±Inf) = +Inf 17 // Hypot(NaN, q) = NaN 18 // Hypot(p, NaN) = NaN 19 func Hypot(p, q float64) float64 20 21 func hypot(p, q float64) float64 { 22 // special cases 23 switch { 24 case IsInf(p, 0) || IsInf(q, 0): 25 return Inf(1) 26 case IsNaN(p) || IsNaN(q): 27 return NaN() 28 } 29 p, q = Abs(p), Abs(q) 30 if p < q { 31 p, q = q, p 32 } 33 if p == 0 { 34 return 0 35 } 36 q = q / p 37 return p * Sqrt(1+q*q) 38 } 39