@atan2(x:numeric, y:numeric) ; listable

The atan2() function computes the principal value of the arc tangent of y/x, using the signs of both arguments to determine the quadrant of the return value.

The atan2() function is used mostly to convert from rectangular $(x,y)$ to polar $(r, \theta)$ coordinates that must satisfy $x = r \cos(\theta)$ and $y = r \sin(\theta)$. In general, conversions to polar coordinates should be computed thus:

        $r := @sqrt($x*$x + $y*$y)
        $theta := @atan2($y, $x).

Mathematical Functions @abs,    @acos,    @asin,    @atan,    @atan2,    @between,    @bit_and,    @bit_or,    @bit_shiftl,    @bit_shiftr,    @ceil,    @clear,    @cos,    @cosh,    @exp,    @floor,    @knn_create,    @knn_rebuild,    @knn_delete,    @knn_rnd,    @knn_search,    @knn_rsearch,    @knn_scan,    @knn_rscan,    @knn_combine,    @knn_rcombine,    @log,    @log10,    @log2,    @max,    @min,    @ode_solve,    @pow,    @rand,    @rand_int,    @random,    @rnd_bernoulli,    @rnd_binomial,    @rnd_exponential,    @rnd_gamma,    @rnd_geometric,    @rnd_normal,    @rnd_uniform_float,    @rnd_uniform_int,    @round,    @sin,    @sinh,    @sqrt,    @tan,    @y0,    @y1