The cadofactor.py script and the factor.sh wrapper can be used to compute
discrete logarithms in a prime field GF(p).

For the moment, it is required to have Magma installed (it seems to fail
with version of Magma before 2.19). It is only capable to handle tiny
examples, since the linear algebra is currently done within Magma. This
should change soon (hopefully). Using the linalg/bwc/bwc-ptrace.sh
script, it might be possible to run the linear algebra step by hand for
larger examples.

In principle, just typing
  ./factor.sh p -dlp
should start a computation of discrete logarithms in GF(p), where p is a
prime of (around) 59 digits. For other sizes, the default parameters may
not be yet available.

A direct use of cadofactor.py allows more flexibility. An example of
parameter file is given in params_dl/param.p59. The main difference is
the presence of the "dlp=true" line, and the lines related to characters
and sqrt disappear.

By default, the script will factor p-1 and compute discrete logs modulo
the largest prime factor ell of p-1. This can be overridden by giving
explicitly ell=... in the parameter file.

The process is automatic up to the reconstruction of logarithms from the
output of the linear algebra and the data remembered during the filtering
phase. The result is in the $wordir/$name.reconstruclog.dlog file.

Individual logarithms, using a descent stage, must be computed by hand
with the help of the sieve/las binary. For that it needs to be recompiled
with DLP_DESCENT and SUPPORT_LARGE_Q (see las-config.h).