I've decided not to use FPVectorial.
But it was only when I upgraded Lazarus that I realised there was a problem.
My App won't compile.
Whatever I do I get an error: Error: Undefined symbol: INIT_FPVECTORIAL_DEF111
I thought I'd removed all traces of the old install, including deleting all configuration files that I could find, but it seems that FPVectorial doesn't let you cast it off that easily.