````// Copyright 2010 The Go Authors. All rights reserved.`
`// Use of this source code is governed by a BSD-style`
`// license that can be found in the LICENSE file.`

`package runtime`

`// inf2one returns a signed 1 if f is an infinity and a signed 0 otherwise.`
`// The sign of the result is the sign of f.`
`func inf2one(f float64) float64 {`
`	g := 0.0`
`	if isInf(f) {`
`		g = 1.0`
`	}`
`	return copysign(g, f)`
`}`

`func complex128div(n complex128, m complex128) complex128 {`
`	var e, f float64 // complex(e, f) = n/m`

`	// Algorithm for robust complex division as described in`
`	// Robert L. Smith: Algorithm 116: Complex division. Commun. ACM 5(8): 435 (1962).`
`	if abs(real(m)) >= abs(imag(m)) {`
`		ratio := imag(m) / real(m)`
`		denom := real(m) + ratio*imag(m)`
`		e = (real(n) + imag(n)*ratio) / denom`
`		f = (imag(n) - real(n)*ratio) / denom`
`	} else {`
`		ratio := real(m) / imag(m)`
`		denom := imag(m) + ratio*real(m)`
`		e = (real(n)*ratio + imag(n)) / denom`
`		f = (imag(n)*ratio - real(n)) / denom`
`	}`

`	if isNaN(e) && isNaN(f) {`
`		// Correct final result to infinities and zeros if applicable.`
`		// Matches C99: ISO/IEC 9899:1999 - G.5.1  Multiplicative operators.`

`		a, b := real(n), imag(n)`
`		c, d := real(m), imag(m)`

`		switch {`
`		case m == 0 && (!isNaN(a) || !isNaN(b)):`
`			e = copysign(inf, c) * a`
`			f = copysign(inf, c) * b`

`		case (isInf(a) || isInf(b)) && isFinite(c) && isFinite(d):`
`			a = inf2one(a)`
`			b = inf2one(b)`
`			e = inf * (a*c + b*d)`
`			f = inf * (b*c - a*d)`

`		case (isInf(c) || isInf(d)) && isFinite(a) && isFinite(b):`
`			c = inf2one(c)`
`			d = inf2one(d)`
`			e = 0 * (a*c + b*d)`
`			f = 0 * (b*c - a*d)`
`		}`
`	}`

`	return complex(e, f)`
`}`
```