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Units

 UseSystem
 set the default system of units

 Calling Sequence UseSystem(system, opts)

Parameters

 system - (optional) symbol; name of system of units opts - (optional) equation of the form $'\mathrm{strict}'=$ true or false; specify options for the system

Description

 • The UseSystem(system, opts) function sets a default system of units to be used in the Standard or Natural environments or in conjunction with the convert/system function for the current session. If a system name is specified, and such a system exists, that system will be set as the default system.
 • To set a default system of units for all future Maple sessions, add the UseSystem command to your Maple initialization file. For more information, see Create Maple Initialization File.
 • The opts argument can contain the following equation.
 'strict'=truefalse
 If this option is set to true, then only units that are part of the given system (including those with SI or IEC prefixes) are accepted in the Natural environment.
 This prevents uncommon units (for example, ph, that is, the phot) from precluding the acceptance of system symbols (for example, ph, that is, the picohour in SI).

Examples

If infolevel is set to a greater integer (possible settings are 1 through 5), more detailed information about the computation method is displayed.

Notes:

 – 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.
 – In Maple 2015 and later versions, the double brackets around a unit are not displayed unless you are editing the unit.
 > $\mathrm{with}\left(\mathrm{Units}\right):$
 > ${\mathrm{infolevel}}_{\mathrm{Units}}≔1$
 ${{\mathrm{infolevel}}}_{{\mathrm{Units}}}{≔}{1}$ (1)
 > $\mathrm{convert}\left(3.23,'\mathrm{system}',\frac{'\mathrm{mi}'}{'h'}\right)$
 convert/system:   "converting to the units m/s"
 ${1.443939200}$ (2)
 > $\mathrm{UseSystem}\left('\mathrm{CGS}'\right)$
 > $\mathrm{convert}\left(3.23,'\mathrm{system}',\frac{'\mathrm{mi}'}{'h'}\right)$
 convert/system:   "converting to the units kyne"
 ${144.3939200}$ (3)
 > $\mathrm{unassign}\left('{\mathrm{infolevel}}_{\mathrm{Units}}'\right)$
 > $\mathrm{with}\left(\mathrm{Units}[\mathrm{Standard}]\right):$
 > $32⟦\frac{'\mathrm{km}'}{'h'}⟧$
 ${32}{}⟦\frac{{\mathrm{km}}}{{h}}⟧$ (4)
 > $\mathrm{combine}\left(,'\mathrm{units}'\right)$
 $\frac{{8000}}{{9}}{}⟦{\mathrm{kyne}}⟧$ (5)
 > $\mathrm{with}\left(\mathrm{Units}[\mathrm{Natural}]\right):$
 > $\mathrm{UseSystem}\left('\mathrm{SI}','\mathrm{strict}'\right)$
 > $\frac{32'\mathrm{cm}'}{'s'}$
 $\frac{{8}}{{25}}{}⟦\frac{{m}}{{s}}⟧$ (6)
 > $\frac{32'\mathrm{mi}'}{'h'}$
 $\frac{{32}{}{\mathrm{mi}}}{{h}}$ (7)