exponential integral function

[James R. V. Z. <jr...@co...>]

I've submitted a patch to add the exponential integral function.
Would someone be willing to accept it?  

I'd apply it myself, but the server won't let me do a commit:

>  cvs login: authorization failed: server gnuplot.cvs.sourceforge.net
>  rejected access to /cvsroot/gnuplot for user vanzandt

It's been a little over a year since I submitted anything, so maybe
I've lost write permissions?  If someone would restore that, I'd
appreciate it.

       - Jim Van Zandt