# Math.Atan Method

.NET Framework 2.0

Returns the angle whose tangent is the specified number.

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

## Syntax

```public static double Atan (
double d
)
```
```public static double Atan (
double d
)
```
```public static function Atan (
d : double
) : double
```

#### Parameters

d

A number representing a tangent.

#### Return Value

An angle, θ, measured in radians, such that -π/2 θπ/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.

## 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/π to convert from radians to degrees.

## Example

```// 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 result;

// Calculate the tangent of 30 degrees.
angle = 30;
Console.WriteLine("The tangent of 30 degrees is {0}.", result);

// Calculate the arctangent of the previous tangent.
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.";

Console.WriteLine(line1, Environment.NewLine);
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()

import System.*;

class Sample
{
public static void main(String[] args)
{
double x = 1.0;
double y = 2.0;
double angle;
double result;

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

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

angle = radians * (180 / Math.PI);

Console.WriteLine(line1, Environment.get_NewLine());
Console.WriteLine(line2, System.Convert.ToString(x),
Console.WriteLine(line3, System.Convert.ToString(angle));
} //main
} //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.
*/

```

## Platforms

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

## Version Information

#### .NET Framework

Supported in: 2.0, 1.1, 1.0

#### .NET Compact Framework

Supported in: 2.0, 1.0