I have installed Texlive 2010 on Ubuntu 10.10 from .iso image. now I want to upgrade my pgf. After following these steps, I receive this error:
! I can't find file `pgfmathfunctions.code.tex'. l.16 \input pgfmathfunctions.code.tex (Press Enter to retry, or Control-D to exit)
I searched that file and found it in pgf's directories. When I copy it beside of my tex file, another error is occurred: the program is unable to find another file; that exists in pgf directories...
sudo texhash after replacing new directories.