Draft Writeup of July 7, 1998

BUILT-IN SUFFIXES


For variables

Suffixes Interpretation
.astatus AMPL status (fixed, presolved, or substituted out)
.defeqn Index in _con of "defining constraint" used to substitute variable out
.dual Dual value on defining constraint of variable substituted out
.init Current initial guess
.init0 Original initial guess (set by := or default or by a data statement)
.lb .ub Current lower & upper bounds
.lb0 .ub0 Initial lower & upper bounds, from the var declaration
.lb1 .ub1 Weaker lower & upper bounds from AMPL's presolve phase
.lb2 .ub2 Stronger lower & upper bounds from AMPL's presolve phase
.lrc .urc Reduced costs at lower & upper bounds
.lslack .uslack Slacks at lower & upper bounds (val - lb and ub - val)
.rc Reduced cost (at the nearer bound)
.slack Bound slack (the lesser of lslack and uslack)
.sstatus Solver status (basis status of variable)
.status AMPL status if not "in", otherwise solver status
.val Current value


For constraints

To define these values unambiguously, all constraints are assumed to be put in the form lower bound <= body <= upper bound, where the the constraint body contains all terms involving variables, and the bounds are constants.

Suffixes Interpretation
.astatus AMPL status (dropped, presolved, or substituted out)
.body Current value of constraint body
.defvar Index in _var of "defined variable" substituted out by the constraint
.dinit Current initial guess for the constraint's dual variable
.dinit0 Original initial guess for the constraint's dual variable
.dual Current value of the constraint's dual variable
.lb .ub Constraint lower & upper bounds
.lbs .ubs Constraint lower & upper bounds sent to solver
(reflecting adjustments for fixed variables)
.ldual .udual Current dual values associated with lower & upper bounds
.lslack .uslack Slacks at lower & upper bounds (body - lb and ub - body)
.slack Constraint slack (the lesser of lslack and uslack)
.sstatus Solver status (basis status of constraint's slack or artificial variable)
.status AMPL status if not "in", otherwise solver status


For objectives

Suffixes Interpretation
.astatus AMPL status
.exitcode Exit code returned by solver after most recent solve with this objective
.message Result message returned by solver after most recent solve with this objective
.result Result string returned by solver after most recent solve with this objective
.val Current value


For problems

Suffixes Interpretation
.astatus AMPL status
.exitcode Exit code returned by solver after most recent solve of this problem
.message Result message returned by solver after most recent solve of this problem
.result Result string returned by solver after most recent solve of this problem


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LAST MODIFIED 7 JULY 1998 BY 4er.