question: static public final float atan2 ( float y , float x ) { float add , mul ; if ( x < 0 ) { if ( y < 0 ) { y = - y ; mul = 1 ; } else { mul = - 1 ; } x = - x ; add = - PI ; } else { if ( y < 0 ) { y = - y ; mul = - 1 ; } else { mul = 1 ; } add = 0 ; } float invDiv = 1 / ( ( x < y ? y : x ) * INV_ATAN2_DIM_MINUS_1 ) ; if ( invDiv == Float . POSITIVE_INFINITY ) { return ( ( float ) Math . atan2 ( y , x ) + add ) * mul ; } int xi = ( int ) ( x * invDiv ) ; int yi = ( int ) ( y * invDiv ) ; return ( Atan2 . table [ yi * ATAN2_DIM + xi ] + add ) * mul ; }
target:  Returns atan2 in radians from a lookup table.