Language reference
Atn (arctangent)
Syntax
Atn(<number>)
π Atn(slope) → angle_rad (Lines)Description
Atn returns the arctangent — the angle (in radians) whose tangent is the input. It is the inverse of Tan, useful for recovering an angle from a slope or ratio.
Technical Description
Atn(x: NUMBER) → NUMBER. Returns atan(x) in radians, in the range (−π/2, π/2) (Math.atan). NULL input returns NULL. PURE, DETERMINISTIC. Floating-point result.
Examples
Angle of a slope, in radians:
π Atn(rise / run) → angle_rad (Lines)PROJECT Atn(rise / run) -> angle_rad (Lines)Convert the result to degrees:
π Degrees(Atn(slope)) → angle_deg (Lines)PROJECT Degrees(Atn(slope)) -> angle_deg (Lines)Limitations
Returns radians in (−π/2, π/2). NUMBER only; NULL in → NULL out. Floating point. It cannot tell (1, 1) from (−1, −1), since both are a ratio of 1: Atan2(y, x) can.
Alternatives
Tan is the forward direction (angle → ratio). Atan2(y, x) takes the two coordinates and returns the angle in the right quadrant.