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// 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
func isposinf(f float64) bool { return f > maxFloat64 }
func isneginf(f float64) bool { return f < -maxFloat64 }
func isnan(f float64) bool { return f != f }
func nan() float64 {
var f float64 = 0
return f / f
}
func posinf() float64 {
var f float64 = maxFloat64
return f * f
}
func neginf() float64 {
var f float64 = maxFloat64
return -f * f
}
func complex128div(n complex128, d complex128) complex128 {
// Special cases as in C99.
ninf := isposinf(real(n)) || isneginf(real(n)) ||
isposinf(imag(n)) || isneginf(imag(n))
dinf := isposinf(real(d)) || isneginf(real(d)) ||
isposinf(imag(d)) || isneginf(imag(d))
nnan := !ninf && (isnan(real(n)) || isnan(imag(n)))
dnan := !dinf && (isnan(real(d)) || isnan(imag(d)))
switch {
case nnan || dnan:
return complex(nan(), nan())
case ninf && !dinf:
return complex(posinf(), posinf())
case !ninf && dinf:
return complex(0, 0)
case real(d) == 0 && imag(d) == 0:
if real(n) == 0 && imag(n) == 0 {
return complex(nan(), nan())
} else {
return complex(posinf(), posinf())
}
default:
// Standard complex arithmetic, factored to avoid unnecessary overflow.
a := real(d)
if a < 0 {
a = -a
}
b := imag(d)
if b < 0 {
b = -b
}
if a <= b {
ratio := real(d) / imag(d)
denom := real(d)*ratio + imag(d)
return complex((real(n)*ratio+imag(n))/denom,
(imag(n)*ratio-real(n))/denom)
} else {
ratio := imag(d) / real(d)
denom := imag(d)*ratio + real(d)
return complex((imag(n)*ratio+real(n))/denom,
(imag(n)-real(n)*ratio)/denom)
}
}
}
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