# Listing Variables, Equations, and Unknowns

To get a list of the equations and defined variables, tap the "List" button or use the "list" command.  The "list" command is used to display the current set of equations, variables (as well as their current lock status), or both.  The command accepts an optional parameter to selectively display certain subsets of information.  Without a parameter, all equations and evaluated variables are listed.

To show the unsolved equations and their unknowns, tap the "Info" button, or use the "info" command.  The "info" command is used to display a status report of the current set of equations.  The info command can be useful in finding good candidate variables to be eliminated, or choosing which equations to use for a substitution.

Listing Variables

To show the definition (if any) of a variable, use the "list" command or enter an expression consisting of the variable itself.

`> list w`
`> list x`
`       x = 11`
`> list x y`
`       x = 11       y = 3`
> e
`  Answer = 2.71828`

Note that no output or error message was generated when "list"ing the undefined variable "w".

To show the definitions of all variables, use the "list variables" command:

`> list variables       x = 11       y = 3       e = 2.71828`

Listing Equations

When multivariate equations are entered, the program keeps track of them by storing them in an equation list.  The "list equations" command shows the equations that have been stored.

`> list equations (Eq. 1)                        9 C               F = 32 + ---                         5 `

The unqualified "list" command can be used to show the stored equation(s) and evaluated variable(s).

`> list (Eq. 1)                        9 C               F = 32 + ---                         5        C = 50       F = 122`

Listing Unknowns

The "info" command is used to display a status report of the current set of equations.  The report includes the following sections:

• A summary line counting the number of equations, variables, and unknowns.
• A numbered list of the unresolved equations alongside their unknowns.
• A list of the current set of unknown variables.
`> info   2 equations in 2 variables (0 locked) with 2 unknowns. * Unresolved equations and their unknowns:   (Eq. 1)   x+y=3   {xy}   (Eq. 2)   x=2y    {xy} * Unknown variables:   x y `

The info command can be useful in finding good candidate variables to be eliminated, or choosing which equations to use for a substitution.

Often, with multiple equations and unknown variables in the workspace, it is useful to know just how much is unknown!  The "list" command is not especially helpful because it does not identify unknowns.  The "info" command is the "list" command's counterpart.  It shows what and how many unresolved equations and variables there are.