ATN2 (Arctangent of Y/X)
The ATN2 function returns the arctangent of y/x.
Syntax
ATN2 ( Y, X )
Example
The example uses ATN2 to calculate Pi. By definition, ATN2(5,5) is 45 degrees; 180 degrees equals Pi radians.
Public Pi 'Declare variables.
BeginProg
Pi = 4 * ATN2( 5, 5
) 'Calculate
Pi.
EndProg
Remarks
ATN2 function calculates the arctangent of Y/X, returning an angle (in radians) in the range of Pi to –Pi. The signs of the parameters determine the quadrant of the returned value.
| Quadrant | Sign Y | Sign X | ATN2 |
|---|---|---|---|
| I | + | + | 0 to Pi/2 |
| II | + | - | Pi/2 to Pi |
| III | - | - | -Pi/2 to -Pi |
| IV | - | + | 0 to –Pi/2 |
ATN2 is defined for every point except the origin (X = 0 and Y = 0). AngleDegrees can be used to return the result of this function in degrees instead of radians.
Pi is approximately 3.141593. To convert degrees to radians, multiply degrees by Pi/180. To convert radians to degrees, multiply radians by 180/Pi.
NOTE: ATN2 is the inverse trigonometric function of TAN, which takes an angle as its argument and returns the ratio of two sides of a right triangle. Do not confuse ATN2 with the cotangent, which is the reciprocal of a tangent (1/tangent).