Download the testing main program 'bisection.f '
Use 'Google' or 'ChatGPT' to find a subroutine for solving your problem.
Search 'fzero' in Netlib
Download fzero.f plus dependencies
Decompress .zip
Copy all .f files to a folder e.g. './sub'
g77 -c ./sub/*.f
Move all .o files to a folder e.g. './obj'
g77 bisection.f ./obj/*.o
a.exe