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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 math

// Nextafter returns the next representable value after x towards y.
// If x == y, then x is returned.
//
// Special cases are:
//      Nextafter(NaN, y) = NaN
//      Nextafter(x, NaN) = NaN
func Nextafter(x, y float64) (r float64) {
        switch {
        case IsNaN(x) || IsNaN(y): // special case
                r = NaN()
        case x == y:
                r = x
        case x == 0:
                r = Copysign(Float64frombits(1), y)
        case (y > x) == (x > 0):
                r = Float64frombits(Float64bits(x) + 1)
        default:
                r = Float64frombits(Float64bits(x) - 1)
        }
        return
}