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Math.Atan Method

Returns the angle whose tangent is the specified number.

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

'Declaration
Public Shared Function Atan ( _
	d As Double _
) As Double

Parameters

d
Type: System.Double
A number representing a tangent.

Return Value

Type: System.Double
An angle, θ, measured in radians, such that -π/2 θ π/2.
-or-
NaN if d equals NaN, -π/2 rounded to double precision (-1.5707963267949) if d equals NegativeInfinity, or π/2 rounded to double precision (1.5707963267949) if d equals PositiveInfinity.

A positive return value represents a counterclockwise angle from the x-axis; a negative return value represents a clockwise angle.

Multiply the return value by 180/Math.PI to convert from radians to degrees.

The following example demonstrates how to calculate the arctangent of a value and display it to the console.


' This example demonstrates Math.Atan()
'                           Math.Atan2()
'                           Math.Tan()
Imports System

Class Sample
   Public Shared Sub Main()
      Dim x As Double = 1.0
      Dim y As Double = 2.0
      Dim angle As Double
      Dim radians As Double
      Dim result As Double

      ' Calculate the tangent of 30 degrees.
      angle = 30
      radians = angle *(Math.PI / 180)
      result = Math.Tan(radians)
      Console.WriteLine("The tangent of 30 degrees is {0}.", result)

      ' Calculate the arctangent of the previous tangent.
      radians = Math.Atan(result)
      angle = radians *(180 / Math.PI)
      Console.WriteLine("The previous tangent is equivalent to {0} degrees.", angle)

      ' Calculate the arctangent of an angle.
      Dim line1 As [String] = "{0}The arctangent of the angle formed by the x-axis and "
      Dim line2 As [String] = "a vector to point ({0},{1}) is {2}, "
      Dim line3 As [String] = "which is equivalent to {0} degrees."

      radians = Math.Atan2(y, x)
      angle = radians *(180 / Math.PI)

      Console.WriteLine(line1, Environment.NewLine)
      Console.WriteLine(line2, x, y, radians)
      Console.WriteLine(line3, angle)
   End Sub 'Main
End Class 'Sample
'
'This example produces the following results:
'
'The tangent of 30 degrees is 0.577350269189626.
'The previous tangent is equivalent to 30 degrees.
'
'The arctangent of the angle formed by the x-axis and
'a vector to point (1,2) is 1.10714871779409,
'which is equivalent to 63.434948822922 degrees.
'


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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