The combine/units command can be used with several modes for combining units, corresponding to subpackages of the Units package. The UseMode(mode) function sets a default mode for combining units, to be used for the current session.

The modes available are currently simple, standard, and natural, corresponding to the Units/Simple, Units/Standard, and Units/Natural subpackages, respectively. If you load any of these packages, Maple will automatically call UseMode with the corresponding argument.

When you load the Units package, Maple will automatically load the subpackage corresponding to the currently selected mode.

Additionally, the mode set by this command determines the default for the symbolic option of the convert/units command. In simple mode, the conversions happen with symbolic = true by default; in the two other modes, the default is symbolic = false.

The default mode if none of these packages have been loaded is simple.

Calling the UseMode command manually can be useful if you use the default Units environment, i.e., without loading any packages, and you wish to select how combine/units should combine units. It can also be useful to do this before loading the Units package, to instruct it which subpackage to load.

The setting effected by the UseMode command applies to any calls to combine/units made by the user themselves, but also to calls from inside other commands, such as plot and int.

The UseMode command returns the previous mode that was in effect. When called without any arguments, its only effect is to return the current mode.

To set a default mode for combining units for all future Maple sessions, add the UseMode command to your Maple initialization file. For more information, see Create Maple Initialization File.

To enter a unit in 2-D Math input, select the unit from the appropriate Units palette. If the unit you want is not there, select $\mathrm{unit}$ and then enter the unit.

When you edit a unit, double brackets appear around it.

$\mathrm{Units}\left[\mathrm{UseMode}\right]\left(\right)$

$\mathrm{simple}$

$\mathrm{combine}\left(\mathrm{distance}+30\mathrm{Unit}\left(\mathrm{km}\right)\,'\mathrm{units}'\right)$

$\mathrm{distance}+30⟦\mathrm{km}⟧$

$\mathrm{Units}\left[\mathrm{UseMode}\right]\left(\mathrm{standard}\right)$

$\mathrm{simple}$

$\mathrm{combine}\left(\mathrm{distance}+30\mathrm{Unit}\left(\mathrm{km}\right)\,'\mathrm{units}'\right)$

Error, (in Units:-Standard:-`+`) the units `1` and `km` have incompatible dimensions

$\mathrm{Units}\left[\mathrm{UseMode}\right]\left(\right)$

$\mathrm{standard}$

$\mathrm{convert}\left(2.4\,'\mathrm{units}'\,'N''m'\left('\mathrm{radius}'\right)\,'\mathrm{Btu}'\right)$

Error, (in `convert/units`) unable to convert `N*m(radius)` to `Btu`

$\mathrm{convert}\left(2.4\,'\mathrm{units}'\,'N''m'\left('\mathrm{radius}'\right)\,'\mathrm{Btu}'\,'\mathrm{symbolic}'='\mathrm{true}'\right)$

$0.002276283395$

$\mathrm{Units}\left[\mathrm{UseMode}\right]\left('\mathrm{simple}'\right)$

$\mathrm{standard}$

$\mathrm{convert}\left(2.4\,'\mathrm{units}'\,'N''m'\left('\mathrm{radius}'\right)\,'\mathrm{Btu}'\right)$

$0.002276283395$

$\mathrm{restart}$

$\mathrm{with}\left(\mathrm{Units}\left[\mathrm{Standard}\right]\right)$

$\left[\mathrm{`*`}\&comma;\mathrm{`+`}\&comma;\mathrm{`-`}\&comma;\mathrm{`/`}\&comma;\mathrm{`<`}\&comma;\mathrm{<=}\&comma;\mathrm{<>}\&comma;\mathrm{`=`}\&comma;\mathrm{\Im }\&comma;\mathrm{\Re }\&comma;\mathrm{`^`}\&comma;\mathrm{abs}\&comma;\mathrm{add}\&comma;\arccos \&comma;\mathrm{arccosh}\&comma;\mathrm{arccot}\&comma;\mathrm{arccoth}\&comma;\mathrm{arccsc}\&comma;\mathrm{arccsch}\&comma;\mathrm{arcsec}\&comma;\mathrm{arcsech}\&comma;\arcsin \&comma;\mathrm{arcsinh}\&comma;\arctan \&comma;\mathrm{arctanh}\&comma;\mathrm{argument}\&comma;\mathrm{ceil}\&comma;\mathrm{collect}\&comma;\mathrm{combine}\&comma;\mathrm{conjugate}\&comma;\cos \&comma;\cosh \&comma;\cot \&comma;\coth \&comma;\csc \&comma;\mathrm{csch}\&comma;\mathrm{csgn}\&comma;\mathrm{diff}\&comma;\mathrm{eval}\&comma;\mathrm{evalc}\&comma;\mathrm{evalr}\&comma;\exp \&comma;\mathrm{expand}\&comma;\mathrm{factor}\&comma;\mathrm{floor}\&comma;\mathrm{frac}\&comma;\mathrm{int}\&comma;\ln \&comma;\log \&comma;\mathrm{log10}\&comma;\mathrm{log2}\&comma;\max \&comma;\min \&comma;\mathrm{mul}\&comma;\mathrm{normal}\&comma;\mathrm{polar}\&comma;\mathrm{root}\&comma;\mathrm{round}\&comma;\sec \&comma;\mathrm{sech}\&comma;\mathrm{seq}\&comma;\mathrm{shake}\&comma;\mathrm{signum}\&comma;\mathrm{simplify}\&comma;\sin \&comma;\sinh \&comma;\mathrm{sqrt}\&comma;\mathrm{surd}\&comma;\tan \&comma;\tanh \&comma;\mathrm{trunc}\&comma;\mathrm{type}\&comma;\mathrm{verify}\right]$

$\mathrm{Units}\left[\mathrm{UseMode}\right]\left(\right)$

$\mathrm{standard}$

$\mathrm{combine}\left(\mathrm{distance}+30\mathrm{Unit}\left(\mathrm{km}\right)\&comma;'\mathrm{units}'\right)$

Error, (in Units:-Standard:-`+`) the units `1` and `km` have incompatible dimensions

$\mathrm{combine}\left(:-\mathrm{`+`}\left(\mathrm{distance}\&comma;30\mathrm{Unit}\left(\mathrm{km}\right)\right)\&comma;'\mathrm{units}'\&comma;'\mathrm{mode}'='\mathrm{simple}'\right)$

$\mathrm{distance}+30⟦\mathrm{km}⟧$

$\mathrm{restart}$

$\mathrm{with}\left(\mathrm{Units}\right)\&colon;$

Automatically loading the Units[Simple] subpackage

$\mathrm{restart}$

$\mathrm{Units}\left[\mathrm{UseMode}\right]\left(\mathrm{standard}\right)$

$\mathrm{simple}$

$\mathrm{with}\left(\mathrm{Units}\right)\&colon;$

Automatically loading the Units[Standard] subpackage

The Units[UseMode] command was introduced in Maple 2017.

For more information on Maple 2017 changes, see Updates in Maple 2017.

The Units[UseMode] command was updated in Maple 2018.