Math.Atan Method
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
Returns the angle whose tangent is the specified number.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- d
- Type: System.Double
A number representing a tangent.
Return Value
Type: System.DoubleAn 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() using System; class Example { public static void Demo(System.Windows.Controls.TextBlock outputBlock) { 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); outputBlock.Text += String.Format("The tangent of 30 degrees is {0}.", result) + "\n"; // Calculate the arctangent of the previous tangent. radians = Math.Atan(result); angle = radians * (180 / Math.PI); outputBlock.Text += String.Format("The previous tangent is equivalent to {0} degrees.", angle) + "\n"; // 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); outputBlock.Text += String.Format(line1, "\n") + "\n"; outputBlock.Text += String.Format(line2, x, y, radians) + "\n"; outputBlock.Text += String.Format(line3, angle) + "\n"; } } /* 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. */