Hi I am running under linux suse kernel 2.4.x What I did was just install the rpm from suse for the package f2c which contains that libray object. Check the Debian distribution on this package Check on your system under the path where mod binaries are ldd -d mod_xxx Anyway even after a suscesfull linking of that objects to produce the binary for modeller I have an error that I reported to Dr Sali and I am awaiting for his reply 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/