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 if p < 0 { 30 p = -p 31 } 32 if q < 0 { 33 q = -q 34 } 35 if p < q { 36 p, q = q, p 37 } 38 if p == 0 { 39 return 0 40 } 41 q = q / p 42 return p * Sqrt(1+q*q) 43 } 44
