The Go programming language uses the **`Nextafter`** function to find the next representable `float64` value between the two arguments it is given, `x` and `y`. `Nextafter` returns the number immediately after `x` and between `x` and `y`. 

To use this function, you must import the `math` package in your file and access the `Nextafter` function within it using the `.` notation (`math.Nextafter`). Here, `Nextafter` is the actual function, while `math` is the Go package that stores the definition of this function.

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## Function definition

The definition of the `Nextafter` function inside the `math` package is as follows:

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## Parameters

The `Nextafter` function takes two arguments of type `float64`:

* `x`: An argument of type `float64`. The `Nextafter` function finds the next representable `float64` value after `x`.


* `y`: An argument of type `float64`. The `Nextafter` function finds the next representable `float64` value after `x` that is in the direction of `y`.

## Return value

The `Nextafter` function returns a single value of type `float64` that represents the next representable `float64` number after `x` that is in the direction of `y`.

Some special cases are when you pass something that is infinity, 0, or `NAN` as an argument:

* If both arguments are the same value, let's say `x`, then `Nextafter` returns that value `x`. 
* If either of the two arguments is of type `NAN`, then the return value is also `NAN`.

## Code

Below is a simple example where we find out the next representable `float64` number after $5.35$ in the direction of $1$:

package main

import(
  "fmt" 
  "math"
) 

func main() {
	var x float64 = 5.35 
	y := math.Nextafter(x,1)
	fmt.Print("The next representable float64 after ", x," is ", y)
}

The example below demonstrates how the `Nextafter` function handles `NAN` values.

> Here, we use the `NaN` function in the `math` package to generate a `NAN` value.



package main

import(
  "fmt" 
  "math"
) 

func main() {
  my_nan := math.NaN()
	y := math.Nextafter(my_nan,1)
	fmt.Print("The next representable float64 after ", my_nan," is ", y)} 

What is the Nextafter function in Golang?

Function definition

Parameters

Return value

Code