abdullah wrote:I think this is the major decision we are taking. The solver representation has to:

1. Offer fast convergence (as opposed to phi parameter).

2. Offer stability.

3. Be convenient when drafting the error functions and partials (allow for simpler representation).

What do we go for as solver representation, Ulrich-DeepSOIC or Mark-DeepSOIC ones?

**The one influenced by Ulrich:**

+ [busted!] all parameters are in mm, may be a pro for convergence.

- parabola case is not covered

- potential problems with moving totally unconstrained ellipse as a whole

+/- slightly more convenient for Cartesian based constraints (we have 2 working and 1 proposed already, and I have in mind a complete system of constraints, including ellipse-tangent-ellipse, using intermediate point (otherwise relatively simple))

**The one influenced by Mark:**

- [busted!] e is dimensionless. But I assume that it will work, since we have circular arcs that work (or maybe we have a millimiter-driven angles there, I don't know!)

++ all conics are covered, including degenerate cases (circle, parabola)

+ easy to move the ellipse as a whole (by dragging it by the focus)

-/+ slightly more convenient for polar-based constraints (we don't have any so far AFAIK, but there may be a possibility to avoid intermediate point (I'm now a big fan of actually using the intermediate point, since it gives a framework for easily implementing tangent and perpendicular constraints between anything, possibly even for Beziers)).

EDIT1: added [busted!] to dimension-related arguments