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A decision variable, for building a program by hand

Source: R/ir.R
var_decl.Rd

Declares one decision variable of a program(). num_var(), int_var() and bin_var() build these for you.

Usage

CONTINUOUS

INTEGER

BINARY

SEMICONTINUOUS

SEMIINTEGER

var_decl(
  name,
  axes = character(),
  domain = CONTINUOUS,
  lower = -Inf,
  upper = Inf,
  start = 0
)

Arguments

name

The variable's name, used for it in the answer.

axes

The names of the index sets the variable is indexed over; character() for a single variable.

domain

CONTINUOUS, INTEGER, BINARY, SEMICONTINUOUS or SEMIINTEGER.

lower, upper

A number (-Inf or Inf for no bound), or the name of a parameter table, for a bound that differs from index to index.

start

The value the search starts from.

Value

var_decl() returns a plain list without a class, with the fields name, axes, domain, lower, upper and start. It is an element of the list a program() takes as vars.

CONTINUOUS, INTEGER, BINARY, SEMICONTINUOUS and SEMIINTEGER are not functions but constants: the whole numbers 1 to 5, which stand for the five kinds of variable in domain.

Details

A variable of domain SEMICONTINUOUS is either 0 or a value between its bounds, and one of domain SEMIINTEGER is either 0 or a whole number between them (see the semi argument of num_var()). Both need finite bounds.

Examples

var_decl("tables", domain = INTEGER, lower = 0)
#> $name
#> [1] "tables"
#> 
#> $axes
#> character(0)
#> 
#> $domain
#> [1] 2
#> 
#> $lower
#> [1] 0
#> 
#> $upper
#> [1] Inf
#> 
#> $start
#> [1] 0
#>