ATAN2: Difference between revisions

Revision as of 23:01, 22 January 2023

The _ATAN2 function returns the radian angle between the positive x-axis of a plane and the point given by the coordinates (x, y).

angle! = _ATAN2(y, x)

y is the vertical axis position (row) as a positive, zero or negative floating point value.
x is the horizontal axis position (column) as a positive, zero or negative floating point value.

The DOUBLE radian angle returned is positive for upper row values where y > 0.

The DOUBLE radian angle returned is 0 when x > 0 and _PI when x < 0 where y = 0
The DOUBLE radian angle returned is negative for lower row values where y < 0.

_ATAN2(0, 0) is undefined and the function returns 0 instead of a division error.

With ATN(y / x), x can never be 0 as that would create a Division by Zero error 11 or #IND.

@@ Line 9: / Line 9: @@
 {{Parameters}}
 * {{Parameter|y}} is the vertical axis position (row) as a positive, zero or negative floating point value.
 * {{Parameter|x}} is the horizontal axis position (column) as a positive, zero or negative floating point value.
@@ Line 17: / Line 17: @@
 ::* _ATAN2(y, x) = [[ATN]](y# / x#) + [[_PI]] when x < 0
 ::* _ATAN2(y, x) = [[_PI]] / 2 when x = 0
 * The [[DOUBLE]] radian angle returned is 0 when x > 0 and [[_PI]] when x < 0 where y = 0
 * The [[DOUBLE]] radian angle returned is '''negative''' for lower row values where y < 0.
 ::* _ATAN2(y, x) = [[ATN]](y# / x#) when x > 0