Can anyone help me to compile a combined f90 and f77 source code using ifc. I can compile f90 and f77 as individual entities, but not together. The errors states undefined reference to all f77 files. By this I imagine that the f90 libraries are not helping f77 compilation. Is there a specific f77 library to which I should refer to in my makefile. Does anybody have experience in compiling f90 with f77. If so I would appreciate your feedback, but please be aware my understanding on this subject is rather poor and I may require a bit more explanation to understand the potential solutions.