github.com/tinygo-org/tinygo@v0.31.3-0.20240404173401-90b0bf646c27/src/runtime/complex.go (about) 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 runtime 6 7 // inf2one returns a signed 1 if f is an infinity and a signed 0 otherwise. 8 // The sign of the result is the sign of f. 9 func inf2one(f float64) float64 { 10 g := 0.0 11 if isInf(f) { 12 g = 1.0 13 } 14 return copysign(g, f) 15 } 16 17 func complex64div(n complex64, m complex64) complex64 { 18 return complex64(complex128div(complex128(n), complex128(m))) 19 } 20 21 func complex128div(n complex128, m complex128) complex128 { 22 var e, f float64 // complex(e, f) = n/m 23 24 // Algorithm for robust complex division as described in 25 // Robert L. Smith: Algorithm 116: Complex division. Commun. ACM 5(8): 435 (1962). 26 if abs(real(m)) >= abs(imag(m)) { 27 ratio := imag(m) / real(m) 28 denom := real(m) + ratio*imag(m) 29 e = (real(n) + imag(n)*ratio) / denom 30 f = (imag(n) - real(n)*ratio) / denom 31 } else { 32 ratio := real(m) / imag(m) 33 denom := imag(m) + ratio*real(m) 34 e = (real(n)*ratio + imag(n)) / denom 35 f = (imag(n)*ratio - real(n)) / denom 36 } 37 38 if isNaN(e) && isNaN(f) { 39 // Correct final result to infinities and zeros if applicable. 40 // Matches C99: ISO/IEC 9899:1999 - G.5.1 Multiplicative operators. 41 42 a, b := real(n), imag(n) 43 c, d := real(m), imag(m) 44 45 switch { 46 case m == 0 && (!isNaN(a) || !isNaN(b)): 47 e = copysign(inf, c) * a 48 f = copysign(inf, c) * b 49 50 case (isInf(a) || isInf(b)) && isFinite(c) && isFinite(d): 51 a = inf2one(a) 52 b = inf2one(b) 53 e = inf * (a*c + b*d) 54 f = inf * (b*c - a*d) 55 56 case (isInf(c) || isInf(d)) && isFinite(a) && isFinite(b): 57 c = inf2one(c) 58 d = inf2one(d) 59 e = 0 * (a*c + b*d) 60 f = 0 * (b*c - a*d) 61 } 62 } 63 64 return complex(e, f) 65 }