ODF1.2 part 1 chapter 20.24 chart:interpolation

[Regina Henschel <rb.henschel@t-online.de>]

Hello members,

the cubic spline interpolation has a wrong description in case of a 
closed line. It should be a periodic spline and the definition should 
contain the condition f_1'(0)=f_n'(n) and f_1''(0)=f_n''(n) as it is the 
rule in mathematics.

This had been discussed in
  http://tools.oasis-open.org/issues/browse/OFFICE-2872

Andreas Guelzow had attached a solution in
http://lists.oasis-open.org/archives/office/201009/msg00819.html
but the current text in ODF1.2 part1 does not contain it, but the wrong 
condition f_1''(0)=3/2*(x_1 + x_{n-1} - 2x_0)=f_n''(n)

I hope that you can correct it, before the text becomes a standard.

Kind regards
Regina Henschel