

   PPiieecceewwiissee PPoollyynnoommiiaall SSpplliinnee RReepprreesseennttaattiioonn

        polySpline(object)
        as.polySpline(object)

   AArrgguummeennttss::

     object: An object that inherits from class `spline'.

   DDeessccrriippttiioonn::

        Create the piecewise polynomial representation of a
        spline object.

   VVaalluuee::

        An object that inherits from class `polySpline'.  This
        is the piecewise polynomial representation of a uni-
        variate spline function.  It is defined by a set of
        distinct numeric values called knots.  The spline func-
        tion is a polynomial function between each successive
        pair of knots.  At each interior knot the polynomial
        segments on each side are constrained to have the same
        value of the function and some of its derivatives.

   AAuutthhoorr((ss))::

        Douglas Bates and Bill Venables

   SSeeee AAllssoo::

        `interpSpline', `periodicSpline', `splineKnots',
        `splineOrder'

   EExxaammpplleess::

        data( women )
        ispl <- polySpline( interpSpline( weight ~ height,  women ) )
        print( ispl )   # print the piecewise polynomial representation
        plot( ispl )    # plots over the range of the knots

