math:atan2

Returns the angle in radians subtended at the origin by the point on a plane with coordinates (x, y) and the positive x-axis, the result being in the range -π to +π. (Note the order of arguments (y, x). There are some maths libraries that implement an atan2 function with the arguments in the order (x, y).

atan2($y as xs:double?, $x as xs:double?) ➔ xs:double?

Arguments
	$y	xs:double?	The supplied angle in radians
	$x	xs:double?	The supplied angle in radians
Result		xs:double?

Namespace

http://www.w3.org/2005/xpath-functions/math

Links to W3C specifications

XPath 3.0 Functions and Operators

XPath 3.1 Functions and Operators

Notes on the Saxon implementation

Implemented since Saxon 9.4; available whether or not XPath 3.0 is enabled. Saxon also (for compatibility) implements the function math:atan2() in namespace http://exslt.org/math.