  In this paper interpolation of two planar points, corresponding tangent
directions and curvatures with Pythagorean-hodograph (PH) curves of degree
seven preserving an arc length is considered. A general approach using complex
representation of PH curves is presented and a detailed analysis of the problem
for data arising from a circular arc is provided. In the case of several
solutions some criteria for the selection of the most appropriate one are
described and an asymptotic analysis is given. Several numerical examples are
included which confirm theoretical results.
