How to read Symbolic equations from a file in fortran ?? I am working on Linux platform. I have a very big equation about two pages. I want to put that equation in a file.txt and then i want my FORTRAN program to read the equation from file.txt instead of making any function or subroutine. Of-course the equation contains many symbols. What should be the syntax of the program to read symbolic equation from a file so that i can calculate or use my equation anywhere anytime in the whole program. I want to say thanks for repliers and all FORTRAN users.