Math.Atan2 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 quotient of two specified numbers.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- y
- Type: System.Double
The y coordinate of a point.
- x
- Type: System.Double
The x coordinate of a point.
Return Value
Type: System.DoubleFor (x, y) in quadrant 1, 0 < θ < π/2.
For (x, y) in quadrant 2, π/2 < θ≤π.
For (x, y) in quadrant 3, -π < θ < -π/2.
For (x, y) in quadrant 4, -π/2 < θ < 0.
If y is 0 and x is not negative, θ = 0.
If y is 0 and x is negative, θ = π.
If y is positive and x is 0, θ = π/2.
If y is negative and x is 0, θ = -π/2.
The following example demonstrates how to calculate the arctangent of an angle and a vector. The resulting value is displayed in the console.
' This example demonstrates Math.Atan() ' Math.Atan2() ' Math.Tan() Class Example Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock) 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) outputBlock.Text &= String.Format("The tangent of 30 degrees is {0}.", result) & vbCrLf ' 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) & vbCrLf ' 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) outputBlock.Text &= String.Format(line1, vbCrLf) & vbCrLf outputBlock.Text &= String.Format(line2, x, y, radians) & vbCrLf outputBlock.Text &= String.Format(line3, angle) & vbCrLf 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. '