I have a number of spreadsheets created in OpenOffice 3.2.0, which have several line charts set to use B-Spline smoothing. The options are set to Resolution = 20, Data Points Order = 3. In open office these display in the expected way. In LibreOffice 4.1.3 they display as chaotic wavy lines. How do I fix this?
See https://bugs.freedesktop.org/show_bug.cgi?id=53875
The old OpenOffice.org algorithm does not exists in ODF1.2. and LO has implemented the way it is specified in ODF1.2. It is possible to implement the old algorithm in LO and add that method to ODF1.3. But you need to find someone to do it. So there is no short time solution.
If you need this special smoothing and do not have OOo3.2 any longer, you can look for a portable version or find the old version in the archive of Apache OpenOffice.
Or you try the new trend line “moving average”, which might work as well, if you have a large data set.