From: Philip Rhoades <phil@pr...>  20090131 06:15:20

Alvin, Alvin Penner wrote: >> The two Bezier quadratics that you could extract from the Inkscape file >> (assuming that the curve representing the function is a single Bezier >> curve segment) > > I am not entirely clear on which way the data is flowing here. Are you > trying to do a curvefit to an existing curve (not in Inkscape) and then > subsequently represent it in svg, or are you drawing a curve in svg and then > trying to represent it as f(x)? Yes. > In any event, just quick comment. The typical svg path element is a cubic > Bezier which can only be represented parametrically as a function of t, not > as an explicit f(x) relationship. However, there is a subset that might be > interesting to look at. If you take a cubic Bezier curve and force the 4 > control points to be equally spaced in the x axis, then what happens is that > x(t) becomes linear and y(t) remains cubic. So you now have an explicit > function y(x) which is still SVGcompatible, and is a cubic polynomial. So > you could do a standard curve fit using cubic polynomials, and still be able > to represent the result in svg. That is exactly what I would like to do!  with other software available this should not be hard? For the particular case I am thinking of, the quadratic would be sufficient. What would be nice is to be able to extract this equation directly from Inkscape . . Regards, Phil.  Philip Rhoades GPO Box 3411 Sydney NSW 2001 Australia Email: phil@... 