# Mathutil

Package mathutil implements some functions for math calculation.

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## Source:

-   [https://github.com/duke-git/lancet/blob/main/mathutil/mathutil.go](https://github.com/duke-git/lancet/blob/main/mathutil/mathutil.go)

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## Example:

```go
import (
    "github.com/duke-git/lancet/v2/mathutil"
)
```

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## Index

-   [Average](#Average)
-   [Exponent](#Exponent)
-   [Fibonacci](#Fibonacci)
-   [Factorial](#Factorial)
-   [Max](#Max)
-   [MaxBy](#MaxBy)
-   [Min](#Min)
-   [MinBy](#MaxBy)
-   [Percent](#Percent)
-   [RoundToFloat](#RoundToFloat)
-   [RoundToString](#RoundToString)
-   [TruncRound](#TruncRound)
-   [Range](#Range)
-   [RangeWithStep](#RangeWithStep)
-   [AngleToRadian](#AngleToRadian)
-   [RadianToAngle](#RadianToAngle)
-   [PointDistance](#PointDistance)
-   [IsPrime](#IsPrime)

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## Documentation

### <span id="Average">Average</span>

<p>Return average value of numbers. Maybe call RoundToFloat to round result.</p>

<b>Signature:</b>

```go
func Average[T constraints.Integer | constraints.Float](numbers ...T) T
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.Average(1, 2)

    avg := mathutil.Average(1.2, 1.4)
    result2 := mathutil.RoundToFloat(avg, 1)

    fmt.Println(result1)
    fmt.Println(result2)

    // Output:
    // 1
    // 1.3
}
```

### <span id="Exponent">Exponent</span>

<p>Calculate x to the nth power.</p>

<b>Signature:</b>

```go
func Exponent(x, n int64) int64
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.Exponent(10, 0)
    result2 := mathutil.Exponent(10, 1)
    result3 := mathutil.Exponent(10, 2)

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)

    // Output:
    // 1
    // 10
    // 100
}
```

### <span id="Fibonacci">Fibonacci</span>

<p>Calculate the nth number of fibonacci sequence.</p>

<b>Signature:</b>

```go
func Fibonacci(first, second, n int) int
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.Fibonacci(1, 1, 1)
    result2 := mathutil.Fibonacci(1, 1, 2)
    result3 := mathutil.Fibonacci(1, 1, 5)

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)

    // Output:
    // 1
    // 1
    // 5
}
```

### <span id="Factorial">Factorial</span>

<p>Calculate the factorial of x.</p>

<b>Signature:</b>

```go
func Factorial(x uint) uint
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.Factorial(1)
    result2 := mathutil.Factorial(2)
    result3 := mathutil.Factorial(3)

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)

    // Output:
    // 1
    // 2
    // 6
}
```

### <span id="Max">Max</span>

<p>Return max value of numbers.</p>

<b>Signature:</b>

```go
func Max[T constraints.Integer | constraints.Float](numbers ...T) T
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.Max(1, 2, 3)
    result2 := mathutil.Max(1.2, 1.4, 1.1, 1.4)

    fmt.Println(result1)
    fmt.Println(result2)

    // Output:
    // 3
    // 1.4
}
```

### <span id="MaxBy">MaxBy</span>

<p>Return the maximum value of a slice using the given comparator function.</p>

<b>Signature:</b>

```go
func MaxBy[T any](slice []T, comparator func(T, T) bool) T
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.MaxBy([]string{"a", "ab", "abc"}, func(v1, v2 string) bool {
        return len(v1) > len(v2)
    })

    result2 := mathutil.MaxBy([]string{"abd", "abc", "ab"}, func(v1, v2 string) bool {
        return len(v1) > len(v2)
    })

    result3 := mathutil.MaxBy([]string{}, func(v1, v2 string) bool {
        return len(v1) > len(v2)
    })

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)

    // Output:
    // abc
    // abd
    //
}
```

### <span id="Min">Min</span>

<p>Return the minimum value of numbers.</p>

<b>Signature:</b>

```go
func Min[T constraints.Integer | constraints.Float](numbers ...T) T
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.Min(1, 2, 3)
    result2 := mathutil.Min(1.2, 1.4, 1.1, 1.4)

    fmt.Println(result1)
    fmt.Println(result2)

    // Output:
    // 1
    // 1.1
}
```

### <span id="MinBy">MinBy</span>

<p>Return the minimum value of a slice using the given comparator function.</p>

<b>Signature:</b>

```go
func MinBy[T any](slice []T, comparator func(T, T) bool) T
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.MinBy([]string{"a", "ab", "abc"}, func(v1, v2 string) bool {
        return len(v1) < len(v2)
    })

    result2 := mathutil.MinBy([]string{"ab", "ac", "abc"}, func(v1, v2 string) bool {
        return len(v1) < len(v2)
    })

    result3 := mathutil.MinBy([]string{}, func(v1, v2 string) bool {
        return len(v1) < len(v2)
    })

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)

    // Output:
    // a
    // ab
    //
}
```

### <span id="Percent">Percent</span>

<p>calculate the percentage of val to total, retain n decimal places.</p>

<b>Signature:</b>

```go
func Percent(val, total float64, n int) float64
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.Percent(1, 2, 2)
    result2 := mathutil.Percent(0.1, 0.3, 2)

    fmt.Println(result1)
    fmt.Println(result2)

    // Output:
    // 0.5
    // 0.33
}
```

### <span id="RoundToFloat">RoundToFloat</span>

<p>Round float up to n decimal places.</p>

<b>Signature:</b>

```go
func RoundToFloat(x float64, n int) float64
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.RoundToFloat(0.124, 2)
    result2 := mathutil.RoundToFloat(0.125, 2)
    result3 := mathutil.RoundToFloat(0.125, 3)

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)

    // Output:
    // 0.12
    // 0.13
    // 0.125
}
```

### <span id="RoundToString">RoundToString</span>

<p>Round float up to n decimal places. will return string.</p>

<b>Signature:</b>

```go
func RoundToString(x float64, n int) string
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.RoundToString(0.124, 2)
    result2 := mathutil.RoundToString(0.125, 2)
    result3 := mathutil.RoundToString(0.125, 3)

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)

    // Output:
    // 0.12
    // 0.13
    // 0.125
}
```

### <span id="TruncRound">TruncRound</span>

<p>Round float off n decimal places.</p>

<b>Signature:</b>

```go
func TruncRound(x float64, n int) float64
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.TruncRound(0.124, 2)
    result2 := mathutil.TruncRound(0.125, 2)
    result3 := mathutil.TruncRound(0.125, 3)

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)

    // Output:
    // 0.12
    // 0.12
    // 0.125
}
```

### <span id="Range">Range</span>

<p>Creates a slice of numbers from start with specified count, element step is 1.</p>

<b>Signature:</b>

```go
func Range[T constraints.Integer | constraints.Float](start T, count int) []T
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.Range(1, 4)
    result2 := mathutil.Range(1, -4)
    result3 := mathutil.Range(-4, 4)
    result4 := mathutil.Range(1.0, 4)

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)
    fmt.Println(result4)

    // Output:
    // [1 2 3 4]
    // [1 2 3 4]
    // [-4 -3 -2 -1]
    // [1 2 3 4]
}
```

### <span id="RangeWithStep">RangeWithStep</span>

<p>Creates a slice of numbers from start to end with specified step.</p>

<b>Signature:</b>

```go
func RangeWithStep[T constraints.Integer | constraints.Float](start, end, step T) []T
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.RangeWithStep(1, 4, 1)
    result2 := mathutil.RangeWithStep(1, -1, 0)
    result3 := mathutil.RangeWithStep(-4, 1, 2)
    result4 := mathutil.RangeWithStep(1.0, 4.0, 1.1)

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)
    fmt.Println(result4)

    // Output:
    // [1 2 3]
    // []
    // [-4 -2 0]
    // [1 2.1 3.2]
}
```

### <span id="AngleToRadian">AngleToRadian</span>

<p>Converts angle value to radian value.</p>

<b>Signature:</b>

```go
func AngleToRadian(angle float64) float64
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.AngleToRadian(45)
    result2 := mathutil.AngleToRadian(90)
    result3 := mathutil.AngleToRadian(180)

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)

    // Output:
    // 0.7853981633974483
    // 1.5707963267948966
    // 3.141592653589793
}
```


### <span id="RadianToAngle">RadianToAngle</span>

<p>Converts radian value to angle value.</p>

<b>Signature:</b>

```go
func RadianToAngle(radian float64) float64
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.RadianToAngle(math.Pi)
    result2 := mathutil.RadianToAngle(math.Pi / 2)
    result3 := mathutil.RadianToAngle(math.Pi / 4)

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)

    // Output:
    // 180
    // 90
    // 45
}
```

### <span id="PointDistance">PointDistance</span>

<p>Caculates two points distance.</p>

<b>Signature:</b>

```go
func PointDistance(x1, y1, x2, y2 float64) float64
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.PointDistance(1, 1, 4, 5)

    fmt.Println(result1)

    // Output:
    // 5
}
```


### <span id="IsPrime">IsPrime</span>

<p>Checks if number is prime number.</p>

<b>Signature:</b>

```go
func IsPrime(n int) bool
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.IsPrime(-1)
	result2 := mathutil.IsPrime(0)
	result3 := mathutil.IsPrime(1)
	result4 := mathutil.IsPrime(2)

	fmt.Println(result1)
	fmt.Println(result2)
	fmt.Println(result3)
	fmt.Println(result4)

	// Output:
	// false
	// false
	// false
	// true
}
```