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        COMMAND LINE OPTIONS FOR MWRANK

Since December 1997, mwrank supports command-line options instead of
prompting the user.  All options have reasonable defaults.

List of command line options, their meaning and default values (set in options.h)

[q, l, t take no parameters; the others take an integer parameter "n"]

-h      help            Displays a summary of this info and quits

-q      quiet mode flag
                        Suppresses the header information (including
                        the date of compilation) which is otherwise output
                        and should be included in any problem/bug reports).
                        Default is off (i.e. not quiet).  Also
                        suppresses prompting for curves

-v n    verbosity level
                        Controls amount of output.  Range 0..3.
                        Default=1.  Level 0 only outputs the rank.
                        Use "-q -v 0" for minimal output, but note
                        that if you also have "-c n" with nonzero n
                        then you will cause a point search to be
                        carried out, but you will not see its results!
                        (Unless -o is used).
                        Details of point search only shown if
                        verbosity is > 1.

-o      output pari     Outputs a very terse summary of the results
                        for use by PARI/GP with suitable interface.
                        Format:
                        Either  [[r],[P1,P2,...,Pr]]
                        where r is the rank and P1,...,Pr are r
                        independent points;
                        or      [[r,r'],[P1,P2,...,Pr]]
                        where r and r' are lower and upper bounds
                        on the rank and P1,...,Pr are r
                        independent points;
                        Can be used in addition to other output
                        options (controlled by -v); for minimal useful
                        output use "-q -v 0 -o"

-p n    precision (#bits)
                        Only relevant for the multiprecision
                        floating point version.  Range 1..large,
                        default 50.  This is bit precision.
                        Stringly recommended to increase for curves
                        with 2-torsion where a second descent is used
                        since then the reduction applied to second
                        descent quartics is more effective.

-b n    height bound for quartic point search.
                        Range 1..15, default 10.

-x n    number of auxiliary primes used for syzygy sieving.
                        Range 0..,default 15.  Only relevant for curves
                        with no 2-torsion.  Worth increasing
                        either for curves with large discriminant, or
                        for curves with suspected large rank r, for
                        which r+1 or r+2 are suitable values.

-l      points output flag.
                        Controls whether generating points are output.
                        Defaults to value of "verbosity", so the only
                        function is to turn this part of the output on
                        when verbosity is 0 (i.e. -v 0 -l).

-t      quartic equivalence test flag.
                        For debugging only.  Default off.

-s      selmer_only     If set, does local tests on homogeneous spaces
                        only, which can be much quicker for curves
                        with 2-torsion.   NB for curves with no
                        2-torsion this computes the 2-Selmer rank
                        exactly;  for curves with 2-torsion it
                        computes an upper bound for the rank based on
                        various Selmer groups, possibly less than that
                        from the 2-Selmer group itself.
                        If unset (the default) then rational points
                        are sought, to give a lower bound for the rank
                        also.

-d     skip_2nd_descent Only relevant for curves with 2-torsion;
                        unset by default.  If set,  does no second
                        descent either locally or globally, which in
                        general gives a larger upper bound for the
                        rank and a smaller lower bound.
                        I recommend setting this if using mwrank with
                        no multiprecision floating point arithmetic.

-S     saturation_bound (non-negative integer or -1) controls saturation
                        0: do no saturation at all
                        n: use n as upper bound for saturation primes
                        -1: allow progam to determine upper bound
                        automatically (but that will be reduced to a
                        default maximum of 100 if it is greater)

Last update: 2016-01-02

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