compact: Remove spurious variables and restrictions
In lintools: Manipulation of Linear Systems of (in)Equalities

compact

R Documentation

Remove spurious variables and restrictions

Description

A system of linear (in)equations can be compactified by removing zero-rows and zero-columns (=variables). Such rows and columns may arise after substitution (see subst_value) or eliminaton of a variable (see eliminate).

Usage

compact(
  A,
  b,
  x = NULL,
  neq = nrow(A),
  nleq = 0,
  eps = 1e-08,
  remove_columns = TRUE,
  remove_rows = TRUE,
  deduplicate = TRUE,
  implied_equations = TRUE
)

Arguments

`A`	[`numeric`] matrix
`b`	[`numeric`] vector
`x`	[`numeric`] vector
`neq`	[`numeric`] The first `neq` rows in `A` and `b` are treated as linear equalities.
`nleq`	[`numeric`] The `nleq` rows after `neq` are treated as inequations of the form `a.x<=b`. All remaining rows are treated as strict inequations of the form `a.x<b`.
`eps`	[`numeric`] Anything with absolute value `< eps` is considered zero.
`remove_columns`	[`logical`] Toggle remove spurious columns from `A` and variables from `x`
`remove_rows`	[`logical`] Toggle remove spurious rows
`deduplicate`	[`logical`] Toggle remove duplicate rows
`implied_equations`	[`logical`] replace cases of `a.x<=b` and `a.x>=b` with `a.x==b`.

Value

A list with the following elements.

A: The compactified version of input A
b: The compactified version of input b
x: The compactified version of input x
neq: number of equations in new system
nleq: number of inequations of the form a.x<=b in the new system
cols_removed: [logical] indicates what elements of x (columns of A) have been removed