Maybe take a look at
this issue, which describes a tortured trek to find a way to get Gnuplot to properly render Π (pi) in an output graphic. Apparently, the gnuplot package is from 2014 and doesn't handle Greek symbols. Why it will use latest-greatest gnuplot 5.2.6 and won't render Greek symbols is mysterious. Also, when executing an org-mode babel gnuplot block, it reports in the minibuffer that it is using Gnuplot 3.7. However, C-c C-c in the block does start up a Gnuplot REPL in Emacs, and output does happen -- just with garbled Greek letters. Odder is when I put the code in a separate file with the mode running, I can get it to render pi correctly with gnuplot-run-file -- but not gnuplot-run-buffer. The latter is garbled, the former good. BTW, a Gnuplot session started at the command line works with Greek symbols just fine.
So I uninstalled gnuplot and installed newer gnuplot-mode (last updated 2017). Testing just a stand-alone file with the code with gnuplot-run-buffer produces good results; however, no REPL in Emacs is started and the gnuplot codeblock in an org file fails. C-c C-c produces
executing Gnuplot code block...
org-babel-execute:gnuplot: Cannot open load file: No such file or directory, gnuplot
obviously Gnuplot in org-mode babel is meant to run with the gnuplot package and not the newer gnuplot-mode package. But now I'm stuck without a way to render Greek letters in a Gnuplot graphic. Something about the gnuplot package doesn't do Greek symbols and something about gnuplot-mode doesn't do org-mode babel gnuplot. Please advise.
LB