The Oakleaf library is distributed in the form of the source code, and must be compiled prior to use.
It is also pre-packaged in GNU/Debian and Ubuntu. The install is, by the way:
    # [sudo] apt install liboakleaf1 liboakleaf-dev liboakleaf-doc
  
  A modern Fortran 2008+ compiler and Minpack are required. Minpack should be installed in the development version, the package is minpack-dev.
Download the source archive, and unpack it:
    $ wget https://integral.physics.muni.cz/pub/oakleaf/oakleaf-1.0.1.tar.gz
    $ tar zxf oakleaf-1.0.1.tar.gz
  
  The Oakleaf library should to be build in the following steps:
    $ cd oakleaf-1.0.1/
    $ ./configure FCFLAGS="-O2 -ffpe-trap=invalid,zero,overflow"
    $ make
    # make install    # as root, or sudo
  
  It can be later un-installed, if the build directory still exists, by command
    $ cd [some directory]/oakleaf-1.0.1/
    # make uninstall    # as root
  
  The building can be customised via optional parameters of the configure. The optimisation "-O2" is reccomended. The library is installed under /usr/local by default (see configure --help).
If Minpack is not found, although installed, by ./configure, try to add LDFLAGS="-L/usr/local/lib" (eventually adjust the path) and check presence of the file libminpack.a.
The Oakleaf package has included a verification. The basic tests can be executed as:
    $ make check
  
  The advanced testing, under a high voltage, is performed by
    $ VOLTAGE=high make check
  
  By default, the library is placed under /usr/local according to the switch --prefix= of ./configure. A program is compiled as
    gfortran -I/usr/local/include .. -L/usr/local/lib ..
  
  If the library is installed by packaging system, --prefix=/usr is selected. For GNU/Debian, as well as derivatives like Ubuntu or Mint, the compile step requires only -I/usr/include:
    gfortran -I/usr/include ..
  
  The library can be found in /usr/lib/<arch>, where the arch x86_64-linux-gnu is just for example.