• Article

Complex.Acos Method

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

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

Syntax

'Declaration
Public Shared Function Acos ( _
    value As Complex _
) As Complex

public static Complex Acos(
    Complex value
)

Parameters

Return Value

Type: System.Numerics.Complex
The angle, measured in radians, which is the arc cosine of value.

Remarks

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

The Acos method uses the following formula:

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

Examples

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

Imports System.Numerics

Module Example
   Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      Dim values() As Complex = { New Complex(.5, 2), 
                                  New Complex(.5, -2),
                                  New Complex(-.5, 2),
                                  New Complex(-.3, -.8) }
      For Each value As Complex In values
         outputBlock.Text += String.Format("Cos(ACos({0})) = {1}", value, 
                           Complex.Cos(Complex.Acos(value))) & vbCrLf 
      Next
   End Sub
End Module
' The example displays the following output:
'       Cos(ACos((0.5, 2))) = (0.5, 2)
'       Cos(ACos((0.5, -2))) = (0.5, -2)
'       Cos(ACos((-0.5, 2))) = (-0.5, 2)
'       Cos(ACos((-0.3, -0.8))) = (-0.3, -0.8)

using System;
using System.Numerics;

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      Complex[] values = { new Complex(.5, 2), 
                           new Complex(.5, -2),
                           new Complex(-.5, 2),
                           new Complex(-.3, -.8) };
      foreach (Complex value in values)
         outputBlock.Text += String.Format("Cos(ACos({0})) = {1}", value,
                           Complex.Cos(Complex.Acos(value))) + "\n";
   }
}
// The example displays the following output:
//       Cos(ACos((0.5, 2))) = (0.5, 2)
//       Cos(ACos((0.5, -2))) = (0.5, -2)
//       Cos(ACos((-0.5, 2))) = (-0.5, 2)
//       Cos(ACos((-0.3, -0.8))) = (-0.3, -0.8)

Version Information

Silverlight

Supported in: 5, 4

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.