The convert(u, unit_free) function returns the unit-free component of u. If u is of type unit, then  is returned.

The convert(u, unit_free, unit) function returns the unit-free component of u and assigns the unit component of u to unit. If u is of type unit, then  is returned. If u is unit-free, then  is assigned to unit.

The term unit-free describes a scalar quantity with no (multiplicative) unit attached to it. Conversion to unit-free does not apply directly to any non-scalar Maple object or data structure, which may still have units embedded within it.