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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

}