gradient of path point

The SVGPathElement object allows to calculate the point p on the path with
respect to the path parameter 'distance' via

getPointAtLength(distance)

see ..
http://www.w3.org/TR/2002/WD-SVG11-20020215/ecmascript-binding.html

It is not uncommon, to be also in need of the path's tangent (gradient) and
possibly the curvature. So two additional method

getTangentAtLength(distance)
getCurvatureAtLength(distance)

would be of great help. Today's SVG implementations should have the
tangential path information for correctly setting markers, so this might be
no great deal.

--
stefan goessner