# decinfo

Describe how entries of matrix variable *X* relate to decision variables

## Syntax

`decX = decinfo(lmisys,X)`

decinfo(lmisys)

## Description

`decinfo`

expresses the entries of a matrix variable
*X* in terms of the decision variables
*x*_{1}, . . .,
*x _{N}*. Recall that the decision variables
are the free scalar variables of the problem, or equivalently, the free entries of all
matrix variables described in

`lmisys`

. Each entry of
*X*is either a hard zero, some decision variable

*x*, or its opposite –

_{n}*x*.

_{n}If `X`

is the identifier of *X* supplied by
`lmivar`

, the command
`decX = decinfo(lmisys,X)`

returns an integer matrix
`decX`

of the same dimensions as *X* whose
(*i, j*) entry is

0 if

*X*(*i, j*) is a hard zero*n*if*X*(*i, j*) =*x*(the_{n}*n*-th decision variable)–

*n*if*X*(*i, j*) = –*x*_{n}

`decX`

clarifies the structure of *X* as well as its
entry-wise dependence on *x*_{1}, . . .,
*x _{N}*. This is useful to specify matrix
variables with atypical structures (see

`lmivar`

).`decinfo`

can also be used in interactive mode by invoking it with
a single argument, as `decinfo(lmisys)`

. It then prompts the user for
a matrix variable and displays in return the decision variable content of this
variable.

## Examples

## Version History

**Introduced before R2006a**