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# ?Vars :: ++Lo..Hi

# EplexInstance: (?Vars :: ++Lo..Hi)

Constrains list elements to lie between the given bounds.
*Vars*
- Variable or number, or a list or submatrix of variables/numbers
*Lo..Hi*
- Lo, Hi are numbers or arithmetic expressions

## Description

Constrain a variable (or all variables in a list) to take only
values in a given range for the eplex instance EplexInstance. Any
variables that are not already problem variables for EplexInstance
will be added to the problem. The range information is passed to
the external solver state associated with EplexInstance as
floats. No type information are implied by the bounds.
In particular, if the bounds are given as integers, this
information is **not** passed to the external solver.
Unless eplex:integers/1 is invoked, any
invocation of the eplex external solver (whether via eplex_solve/1,
lp_solve/2, lp_demon_setup/5 or optimize/2) will only solve a
continuous relaxation, even when problem variables have been
declared as integers in other solvers (e.g. ic).

No propagation is done at the ECLiPSe level with the bounds. In
particular, the variable is not instantiated even if the lower and
upper bounds are identical. The bounds may be inconsistent with the
bounds given for the variables in other EplexInstances or solvers
(i.e. this will not result in immediate failure).

### Fail Conditions

Lo is greater than Hi.
### Exceptions

*(5) type error *
- Lo..Hi is not in correct form
*(5) type error *
- Lo and Hi are of different numeric types

## See Also

integers / 1, reals / 1, fd_sets : :: / 2, suspend : :: / 2, ic_sets : :: / 2, ic : :: / 2, gfd : :: / 2, ic_hybrid_sets : :: / 2, fd : :: / 2, suspend : #:: / 2, ic : #:: / 2, gfd : #:: / 2, fd : #:: / 2, $:: / 2, get_var_bounds / 3