Hi I just installed Modeller4 under linux kernel 2.4.x the only problem I have is executing > soft/modeller4/bin/mod4 model-default /soft/modeller4/bin/mod_i386-linux: error while loading shared libraries: /soft/modeller4/bin/mod_i386-linux: undefined symbol: acos check libs and it seems I have the right set of linked libs ldd -d mod_i386-linux /lib/libNoVersion.so.1 => /lib/libNoVersion.so.1 (0x40017000) libf2c.so.0 => /usr/lib/libf2c.so.0 (0x40034000) libc.so.6 => /lib/libc.so.6 (0x4004b000) /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000) Any ideas on this Delmiro -- Dr. Delmiro Fernandez-Reyes National Institute for Medical Research Division of Mathematical Biology The Ridgeway, Mill Hill, London NW7 1AA Tel: +44 020 89593666 ext. 2632 Tel: +44 020 89138711 Direct Fax: +44 020 89138545 http://mathbio.nimr.mrc.ac.uk/