# Complex.Asin Method (Complex)

.NET Framework (current version)

Returns the angle that is the arc sine of the specified complex number.

Namespace:   System.Numerics
Assembly:  System.Numerics (in System.Numerics.dll)

## Syntax

```public static Complex Asin(
Complex value
)
```

#### Parameters

value
Type: System.Numerics.Complex

A complex number.

#### Return Value

Type: System.Numerics.Complex

The angle which is the arc sine of value.

## Remarks

The Asin method for complex numbers corresponds to the Math.Asin method for real numbers.

The Asin method uses the following formula:

-ImaginaryOne * Log(ImaginaryOne * value + Sqrt(One - value * value))

## Examples

The following example illustrates the Asin method. It shows that passing the value returned by the Asin method to the Sin method returns the original Complex value.

```using System;
using System.Numerics;

public class Example
{
public static void Main()
{
Complex[] values = { new Complex(2.3, 1.4),
new Complex(-2.3, 1.4),
new Complex(-2.3, -1.4),
new Complex(2.3, -1.4) };
foreach (Complex value in values)
Console.WriteLine("Sin(Asin({0})) = {1}",
value, Complex.Sin(Complex.Asin(value)));
}
}
// The example displays the following output:
//       Sin(Asin((2.3, 1.4))) = (2.3, 1.4)
//       Sin(Asin((-2.3, 1.4))) = (-2.3, 1.4)
//       Sin(Asin((-2.3, -1.4))) = (-2.3, -1.4)
//       Sin(Asin((2.3, -1.4))) = (2.3, -1.4)
```

## Version Information

Universal Windows Platform
Available since 8
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 4.0
Windows Phone
Available since 8.1