# Golang math.Y1() Function with Examples

Golang | math.Y1() Function: Here, we are going to learn about the Y1() function of the math package with its usages, syntax, and examples.
Submitted by IncludeHelp, on September 04, 2021

## math.Y1()

The Y1() function is an inbuilt function of the math package which is used to get the order-one Bessel function of the second kind.

It accepts a parameter (x) and returns the order-one Bessel function of the second kind.

Syntax:

```func Y1(x float64) float64
```

Parameter(s):

• x : The value to be used to get the order-one Bessel function of the second kind.

Return Value:

The return type of Y1() function is a float64, it returns the order-one Bessel function of the second kind.

Special cases:

• Y1(+Inf) = 0
If the parameter is +Inf, the function returns 0.
• Y1(0) = -Inf
If the parameter is 0, the function returns -Inf.
• Y1(x < 0) = NaN
If the parameter is less than 0, the function returns NaN.
• Y1(NaN) = NaN
If the parameter is NaN, the function returns the same value (NaN).

Example 1:

```// Golang program to demonstrate the
// example of math.Y1() Function

package main

import (
"fmt"
"math"
)

func main() {
fmt.Println(math.Y1(1))
fmt.Println(math.Y1(1.5))
fmt.Println(math.Y1(5))

fmt.Println(math.Y1(-1))
fmt.Println(math.Y1(-1.5))
fmt.Println(math.Y1(-5))

fmt.Println(math.Y1(0))
fmt.Println(math.Y1(math.Inf(1)))
fmt.Println(math.Y1(math.Inf(-1)))
fmt.Println(math.Y1(math.NaN()))
}
```

Output:

```-0.7812128213002887
-0.4123086269739113
0.1478631433912268
NaN
NaN
NaN
-Inf
0
NaN
NaN
```

Example 2:

```// Golang program to demonstrate the
// example of math.Y1() Function

package main

import (
"fmt"
"math"
)

func main() {
var x float64
var Y1X float64

x = 1
Y1X = math.Y1(x)
fmt.Println("Y1(", x, ") = ", Y1X)

x = 10.5
Y1X = math.Y1(x)
fmt.Println("Y1(", x, ") = ", Y1X)

x = 0
Y1X = math.Y1(x)
fmt.Println("Y1(", x, ") = ", Y1X)

x = math.NaN()
Y1X = math.Y1(x)
fmt.Println("Y1(", x, ") = ", Y1X)

x = math.Inf(1)
Y1X = math.Y1(x)
fmt.Println("Y1(", x, ") = ", Y1X)

x = math.Inf(-1)
Y1X = math.Y1(x)
fmt.Println("Y1(", x, ") = ", Y1X)
}
```

Output:

```Y1( 1 ) =  -0.7812128213002887
Y1( 10.5 ) =  0.23370422835726865
Y1( 0 ) =  -Inf
Y1( NaN ) =  NaN
Y1( +Inf ) =  0
Y1( -Inf ) =  NaN
```