---------------------------------------------------------- HOPPET: Higher Order Perturbative Parton Evolution Toolkit ---------------------------------------------------------- HOPPET is a Fortran 95 package for carrying out DGLAP evolution and other common manipulations of parton distribution functions (PDFs). Within HOPPET, PDFs are represented on a grid in x-space so as to avoid limitations on the functional form of input distributions. Decent speed and accuracy are obtained through the representation of splitting functions in terms of their convolution with a set of piecewise polynomial basis functions, and Runge-Kutta techniques are used for the evolution in Q. Unpolarised evolution is provided in the MSbar scheme to NNLO in the coupling, including heavy-quark thresholds, and polarised evolution to NLO. The code is structured so as to provide simple access to the objects representing splitting function and PDFs, making it possible for a user to extend the facilities already provided. The latest version can always be obtained from svn checkout http://svn.hepforge.org/hoppet/trunk hoppet Details of changes are to be found in the file ChangeLog, while summaries of changes between releases are in ReleaseNotes. ---------------------------------------------------------------------- F95 compilers ------------- You will need a Fortran 95 compiler to compile this package. The free g95 (www.g95.org) compiler is one option, though its executables are fairly slow. It is easy to install if you don't already have a recent version on your system. The gfortran compiler is becoming fairly widespread. Versions upwards of a recent 4.3 are OK. Older versions generate incorrect code for HOPPET and should be avoided. The code is acceptably fast, though not quite as fast as with commercial compilers. The intel (ifort) compiler (versions 8.1.033 upwards) exists in a semi-free version for non-commercial use under linux and produces fast executables. The release has also been tested with the lahey lf95 commercial compiler, which also generates fast code. Compilation ----------- For details see the INSTALL file. To get moving quickly, just specify an installation prefix and a fortran compiler (FC), and then do ./configure --prefix="..." FC="..." make make check make install [if you're interested] This is not autotools based: if you're used to more advanced usage of autotools scripts, you'll be disappointed here... Example programs ---------------- The main example program is examples_f90/tabulation_example.f90 An equivalent program with the startup, pdf initialisation and evolution spread across different subroutines is given as tabulation_example_2. An equivalent program based on the streamlined interface is given as tabulation_example_streamlined. Compiling f77 example programs (examples_f77) using g77 is a little trickier because of the need to include the correct f95 libraries. Accordingly the Makefile is not generated automatically -- look inside the suppplied Makefile to see what needs doing. cd ../example_f77 # # compile make tabulation_example # run the program should give output identical to that from # example_f90/tabulation_example ./tabulation_example In the same directory there is a C++ example make cpp_tabulation_example ./cpp_tabulation_example which again does the same things (though in this case it uses the simpler of the two vanilla initialization calls). Other programs provided in the example_f77/ directory illustrate the use of the vanilla interface in conjunction with LHAPDF (compare_lhapdf_hoppet.f), and show how use the feature of getting convolutions with splitting functions (convolution_example.f). ---------------------------------------------------------------------- Documentation ------------- Detailed documentation is available as doc/HOPPET-v1-doc.tex . ---------------------------------------------------------------------- Benchmarking ------------ The benchmarking/ directory contains the programs used for the full benchmarking, accuracy and precision testing.