LGO Options¶
ampl: option solver lgo; # change the solver
ampl: option lgo_options 'option1=value1 option2=value2'; # specify options
ampl: solve; # solve the problem
Solver options obtained with $ lgo -=.
con_tol max. constraint violation in local search; default 1e-8
fi_tol local search merit function precision improvement target;
default = 1e-8
flog name of log file for function evaluations (debug option,
default = not written)
g_maxfct factor affecting max. merit function evals in global phase.
The limit is often 2*g_maxfct but may be more when the starting
point is infeasible. Default g_maxfct = 50*(m+n+2)^2, in which
n = _snvars (number of decision variables the solver sees)
and m = _sncons (number of constraints the solver sees).
g_target global search target objective function value; default -1e10
irngs random number seed (default 0) for LGO's built-in random-number
generator
kt_tol local Kuhn-Tucker optimality tolerance; default 1e-8
l_maxfct max. merit function evals in global phase; default 50*(m+n+2)^2,
with m and n as for g_maxfct
l_target local search target objective function value; default -1e10
lbound lower bound imposed on variables unbounded below:
change -Infinity <= x <= U
to min(0,U) + lbound <= x <= U;
default lbound = -1e4
linwarn Whether to warn about or object to purely linear problems:
sum of
1 = yes (default)
2 = abort execution if purely linear
4 = abort execution if integer variables are present
logfile name of log file written when outlev >= 3 (default "LGO.LOG")
maxnosuc limit on global phase merit evals without improvement;
default = 50*(m+n+2)^2
objno objective number: 1 = first (default)
objrep Whether to replace
minimize obj: v;
with
minimize obj: f(x)
when variable v appears linearly
in exactly one constraint of the form
s.t. c: v >= f(x);
or
s.t. c: v == f(x);
Possible objrep values:
0 = no
1 = yes for v >= f(x)
2 = yes for v == f(x)
3 = yes in both cases (default)
opmode synonym for "search" (see below)
outfile name of file written when outlev >= 2 (default "LGO.OUT")
outlev output level:
0 (default) ==> no output
1 ==> write sumfile
2 ==> also outfile
3 ==> also logfile
penmult constraint penalty multiplier; default 1.0
search search kind:
0 = just local optimization
1 = global branch-and-bound + local optimization
2 = global adaptive random + local optimization
3 = multi-start local search (default)
sumfile name of summary file written when outlev >= 1 (default "LGO.SUM")
timelim time limit in seconds; default 300
timing report I/O and solution times: 1 = stdout, 2 = stderr, 3 = both
ubound upper bound imposed on variables unbounded above:
change L <= x <= Infinity
to L <= x <= max(L,0) + ubound;
default ubound = 1e4
version single-word phrase: show the current version
wantsol solution report without -AMPL: sum of
1 ==> write .sol file
2 ==> print primal variable values
4 ==> print dual variable values
8 ==> do not print solution message