Re: atan2 function

[Thangalin via ntg-context <ntg-context@ntg.nl>]

I don't think an atantwo is needed. I *thought* I had read somewhere
that atan( y, x ) was equivalent to calling atan2 in Lua. Ensuring
there's no breakage when x == y would be nice, though. It was a little
surprising to see angle return degrees rather than radians, but it
does simplify my code:

      dc := vbc - vac;
      dr := vbr - var;
      vi := 0;

      if not( dc == dr ):
        vi := round( angle( dc, dr ) / 60 );
      fi;

      % Compute the direction towards the first segment (to vertex of an edge).
      vangle := vi * 60 * pi / 180;

Even simpler would be:

      dc := vbc - vac;
      dr := vbr - var;
      vi := round( angle( dc, dr ) / 60 ); % returns 0 when dc == dr

      % Compute the direction towards the first segment (to vertex of an edge).
      vangle := vi * 60 * pi / 180;

Or accepting a third argument as the return value in the special case:

      vi := round( angle( dc, dr, 0 ) / 60 ); % returns 0 when dc == dr

Cheers!
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