The program root_search.f90 finds the roots of a function by bisection.

It is composed by:

module rootfinding.f90 It contains the subroutine bisect. Subroutines for root searching with other methods could be added here

module functions.f90 It contains the function f=x^2-5. Other functions could be added

main program zero_of_f.f90 Read interval where the root occurs and the desired tolerance from file root_search.inp.
Calls the subroutine bisect and writes results to file root_search.out
Reading the input from an external file avoids recompiling the program.
It is good practice to write the input data in the output file.

Since modules can be used by different main programs they can be stored separately and compiled together by use of makefile and the command make.

module rootfinding.f90	It contains the subroutine bisect. Subroutines for root searching with other methods could be added here
module functions.f90	It contains the function f=x^2-5. Other functions could be added
main program zero_of_f.f90	Read interval where the root occurs and the desired tolerance from file root_search.inp. Calls the subroutine bisect and writes results to file root_search.out Reading the input from an external file avoids recompiling the program. It is good practice to write the input data in the output file.