Use the type command to determine if a package is implemented as a module or as a table.

type(packagename, `module`);

type(packagename, table);

For example,

type(networks, '`module`');

$\mathrm{false}$

type(VectorCalculus, '`module`');

$\mathrm{true}$

Once you have determined how the package has been implemented, follow the instructions in one of the following sections.

Packages Implemented as Modules

Packages Implemented as Tables

To use a top-level command after its name has been rebound to a package-level command, use the colon-dash syntax (:-commandname).

The following example intentionally employs an error message to illustrate which command level is used.

diff( );

Error, invalid input: diff expects 2 or more arguments, but received 0

Note: The message refers to the top-level diff command.

Now invoke the VectorCalculus package.

with(VectorCalculus);

$\left[\mathrm{\&x}\&comma;\mathrm{`*`}\&comma;\mathrm{`+`}\&comma;\mathrm{`-`}\&comma;\mathrm{`.`}\&comma;\mathrm{<,>}\&comma;\mathrm{<|>}\&comma;\mathrm{About}\&comma;\mathrm{AddCoordinates}\&comma;\mathrm{ArcLength}\&comma;\mathrm{BasisFormat}\&comma;\mathrm{Binormal}\&comma;\mathrm{ConvertVector}\&comma;\mathrm{CrossProduct}\&comma;\mathrm{Curl}\&comma;\mathrm{Curvature}\&comma;\mathrm{D}\&comma;\mathrm{Del}\&comma;\mathrm{DirectionalDiff}\&comma;\mathrm{Divergence}\&comma;\mathrm{DotProduct}\&comma;\mathrm{Flux}\&comma;\mathrm{GetCoordinateParameters}\&comma;\mathrm{GetCoordinates}\&comma;\mathrm{GetNames}\&comma;\mathrm{GetPVDescription}\&comma;\mathrm{GetRootPoint}\&comma;\mathrm{GetSpace}\&comma;\mathrm{Gradient}\&comma;\mathrm{Hessian}\&comma;\mathrm{IsPositionVector}\&comma;\mathrm{IsRootedVector}\&comma;\mathrm{IsVectorField}\&comma;\mathrm{Jacobian}\&comma;\mathrm{Laplacian}\&comma;\mathrm{LineInt}\&comma;\mathrm{MapToBasis}\&comma;\nabla \&comma;\mathrm{Norm}\&comma;\mathrm{Normalize}\&comma;\mathrm{PathInt}\&comma;\mathrm{PlotPositionVector}\&comma;\mathrm{PlotVector}\&comma;\mathrm{PositionVector}\&comma;\mathrm{PrincipalNormal}\&comma;\mathrm{RadiusOfCurvature}\&comma;\mathrm{RootedVector}\&comma;\mathrm{ScalarPotential}\&comma;\mathrm{SetCoordinateParameters}\&comma;\mathrm{SetCoordinates}\&comma;\mathrm{SpaceCurve}\&comma;\mathrm{SurfaceInt}\&comma;\mathrm{TNBFrame}\&comma;\mathrm{TangentLine}\&comma;\mathrm{TangentPlane}\&comma;\mathrm{TangentVector}\&comma;\mathrm{Torsion}\&comma;\mathrm{Vector}\&comma;\mathrm{VectorField}\&comma;\mathrm{VectorPotential}\&comma;\mathrm{VectorSpace}\&comma;\mathrm{Wronskian}\&comma;\mathrm{diff}\&comma;\mathrm{eval}\&comma;\mathrm{evalVF}\&comma;\mathrm{int}\&comma;\mathrm{limit}\&comma;\mathrm{series}\right]$

The VectorCalculus package contains a diff command. For differences between the two commands, see diff and VectorCalculus:-diff.

Enter the diff(); command again.

diff();

Error, invalid input: VectorCalculus:-diff uses a 1st argument, f, which is missing

The message now indicates that the error is generated by the VectorCalculus package-level command and not the top-level diff command.

To use the top-level diff command, use the :- syntax.

:-diff();

Error, invalid input: diff expects 2 or more arguments, but received 0

Note: The message once again indicates that the error is generated by the top-level diff function.

To use a top-level command after its name has been rebound to a package-level command, you must first use the restart; command.

The following example intentionally employs an error message to illustrate which command level is used.

minimize();

Error, invalid input: minimize uses a 1st argument, exprFP (of type algebraic), which is missing

Note: The message refers to the top-level minimize command.

with(simplex);

$\left[\mathrm{basis}\&comma;\mathrm{convexhull}\&comma;\mathrm{cterm}\&comma;\mathrm{define\_zero}\&comma;\mathrm{display}\&comma;\mathrm{dual}\&comma;\mathrm{feasible}\&comma;\mathrm{maximize}\&comma;\mathrm{minimize}\&comma;\mathrm{pivot}\&comma;\mathrm{pivoteqn}\&comma;\mathrm{pivotvar}\&comma;\mathrm{ratio}\&comma;\mathrm{setup}\&comma;\mathrm{standardize}\right]$

The simplex package contains a minimize command.

minimize();

Error, invalid input: minimize uses a 1st argument, obj, which is missing

Note: The message refers to the package-level simplex[minimize] command.

:-minimize();

Error, invalid input: minimize uses a 1st argument, obj, which is missing

Note: Packages implemented as tables overwrite any conflicting top-level commands when you invoke the package. You cannot access the top-level command by using the :- syntax.

To use the top-level minimize command, first invoke the restart command.

restart;

minimize();

Error, invalid input: minimize uses a 1st argument, exprFP (of type algebraic), which is missing

Note: The message once again refers to the top-level minimize command.