Options are passed to the code by means of a structure opt.
It is important to set the options correctly in order to take full
advantage of the codes. Particular attention should be paid to the
termination options 
, 
and 
, for which
appropriate values are quite problem dependent.
All options are set to their default values by calling the
routine setopt.m. The default values demand high accuracy;
the number of iterations required to meet the termination criteria is reduced
by requesting less accurate solutions.
(see below), then explicitly setting
results in data validation alone.
(see (5))
is reduced by approximately a factor of 
per iteration
in the last few iterations.
)
and 
set to
larger initial values (see below). This is done automatically when the
driver script sql.m is used, but is not done if the the
driver script is bypassed with a direct call to the function
fsql.m.
) 
) 
(see (6)). reltol is usually set to a value smaller than that of abstol. Successful termination takes place when both the absolute and relative conditions are satisfied. Either one can be relaxed by making the corresponding tolerance large.
is less than the previous value of divided by
gapprogtol, then the progress is considered ``sufficient''. This
check is performed only when has been reduced below 100 times
the value of abstol.
is less than
feasprogtol times the previous , or the new 
is
less than feasprogtol times the previous , then the loss
of feasibility, if any, is considered ``tolerable''.
Termination occurs if the loss of feasibility was not
``tolerable'' and the reduction in was not ``sufficient'' to
justify this loss of feasibility. In short, for the default values,
these conditions mean that we are not willing to let the algorithm
continue if the primal or dual infeasibility worsened by a factor
of 5 or more, unless the gap improved by a factor of at least 100.
These options attempt to achieve a judicious balance between feasibility
and complementarity by trading the former in return for the latter.
)
or in 
(see (6)) becomes
greater than , the algorithm terminates. Unbounded primal (dual)
feasible iterates suggest that the dual (primal) program may be infeasible.
Setting to 1 produces one line of output per
iteration (iteration number, primal and dual step lengths, primal and
dual infeasibilities and , the inner product ,
and primal and dual objective values).
Upon termination, summary information is provided by the script sql.m
regardless of the value of .
, fsql.m
makes a check to ensure the initial 
and 
conform to the block
diagonal structure specified.
has only one block, or its blocks
are all relatively small.
When the default value -1 is used, the code automatically decides
whether or not to use this mex file; the user may override this
by specifying a value of 0 (do not use it) or 1 (use it).