Math.Atan(Double) Method

Definition

Namespace:

System

Assembly:

System.Runtime.dll

Source:

Math.cs

Returns the angle whose tangent is the specified number.

public:
 static double Atan(double d);

public static double Atan (double d);

static member Atan : double -> double

Public Shared Function Atan (d As Double) As Double

Parameters

d

Double

A number representing a tangent.

Returns

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.

Examples

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()
using namespace System;
int main()
{
   double x = 1.0;
   double y = 2.0;
   double angle;
   double radians;
   double result;
   
   // 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.
   String^ line1 = "{0}The arctangent of the angle formed by the x-axis and ";
   String^ line2 = "a vector to point ({0},{1}) is {2}, ";
   String^ line3 = "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 );
}

/*
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.
*/

// This example demonstrates Math.Atan()
//                           Math.Atan2()
//                           Math.Tan()
using System;

class Sample
{
    public static void Main()
    {
    double x = 1.0;
    double y = 2.0;
    double angle;
    double radians;
    double result;

// 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.
    String line1 = "{0}The arctangent of the angle formed by the x-axis and ";
    String line2 = "a vector to point ({0},{1}) is {2}, ";
    String line3 = "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);
    }
}
/*
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.
*/

// This example demonstrates Math.Atan()
//                           Math.Atan2()
//                           Math.Tan()
// Functions 'atan', 'atan2', and 'tan' may be used instead. 
open System

[<EntryPoint>]
let main _ =
    let x = 1.
    let y = 2.

    // Calculate the tangent of 30 degrees.
    let angle = 30.
    let radians = angle * (Math.PI / 180.)
    let result = Math.Tan radians
    printfn $"The tangent of 30 degrees is {result}."

    // Calculate the arctangent of the previous tangent.
    let radians = Math.Atan result
    let angle = radians * (180. / Math.PI)
    printfn $"The previous tangent is equivalent to {angle} degrees."

    // Calculate the arctangent of an angle.

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

    printfn 
        $"""The arctangent of the angle formed by the x-axis and 
a vector to point ({x},{y}) is {radians},
which is equivalent to {angle} degrees."""
    0

//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.

' This example demonstrates Math.Atan()
'                           Math.Atan2()
'                           Math.Tan()
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
End Class
'
'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.
'

Remarks

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.

This method calls into the underlying C runtime, and the exact result or valid input range may differ between different operating systems or architectures.