HI,No; it was never supported by gnuplot, as gnuplot doesn't have modified Bessel functions.
I have 2 questions concerning gnuplot:
1. The bessel function seems not to work in gnuplot. Is that a bug or due to gnuplot?
No; but gnuplot does have mailing lists, start looking at http://www.gnuplot.info
2. Gnuplot seems very slow on my SuSE Linux 8.2 system whereas it is much faster on my Redhat Linux 7.3 system? Any ideas why?