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Manuscript Title: A Higher Order Perturbative Parton Evolution Toolkit (HOPPET)
Authors: G.P. Salam, J. Rojo
Program title: HOPPET
Catalogue identifier: AECA_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 180(2009)120
Programming language: Fortran 95.
Computer: All.
Operating system: All.
RAM: ~< 10MB
Keywords: unpolarised and longitudinally polarised parton space-like distribution functions (PDFs), DGLAP evolution equations, x-space solutions.
PACS: 12.38.Bx, 12.38.-t.
Classification: 11.5.

Nature of problem:
Solution of the DGLAP evolution equations up to NNLO (NLO) for unpolarised (longitudinally polarised) PDFs, and provision of tools to facilitate manipulation (convolutions, etc.) of PDFs with user-defined coefficient and splitting functions.

Solution method:
Representation of PDFs on a grid in x, adaptive integration of splitting functions to reduce them to a discretised form, obtaining fast convolutions that are equivalent to integration with an interpolated form of the PDFs; Runge Kutta solution of the Q evolution, and its caching so as to speed up repeated evolution with different initial conditions.

PDFs should be smooth on the scale of the discretisation in x.

Running time:
a few seconds for initialisation, then ~ 10 ms for creating a tabulation with a relative accuracy of 10-4 from a new initial condition (on a 3.4 GHz Pentium IV processor). Further details in section 9.2.