Feature	Mathcad 13	Mathcad 12	Mathcad 11
Range Variables with Units Require an Explicit Step Size	Range variables with units must specify a step size.	Range variables with units must specify a step size.	Range variables with units use the base unit for a step size if not supplied.
Regression and ODE Solvers Don't Accept Units	All units must balance in any function call, including the outputs generated by calling argument functions.	All units must balance in any function call, including the outputs generated by calling argument functions.	Functions that accept other functions as arguments don't unit balance the output of the argument function.
UnitsOf and SIUnitsOf Functions	UnitsOf restored in the SI system. SIUnitsOf returns the base SI unit for any quantity, regardless of worksheet unit system. UnitsOf replaced with SIUnitsOf function, which returns the base SI unit for any quantity, regardless of worksheet unit system. UnitsOf function returns the base unit for any quantity in the worksheet unit system.	UnitsOf replaced with SIUnitsOf function, which returns the base SI unit for any quantity, regardless of worksheet unit system.	UnitsOf function returns the base unit for any quantity in the worksheet unit system.
Unit Simplification Rules	User-defined default units let you choose unit simplification rules.	1/s does not simplify, to avoid confusion with angular frequency Hz.	1/s simplified to Hz.
Solve Blocks with Mixed-Unit Results Must Be Assigned Differently	"Mixed-unit results" must be independently assigned, including parametric functions to calculate results.	"Mixed-unit results" must be independently assigned, cannot be parameterized.	"Mixed-unit results" from a solve block can be displayed or parameterized.
Solve Blocks with Units May Fail to Converge Due to Scaling	Values in solve blocks are scaled to SI before solving.	Values in solve blocks are scaled to SI before solving.	Values in solve blocks are scaled to the worksheet unit system before solving.
Solve Blocks with Zero Guess Values Produces Unitless Results	Guess values of 0 with units strip the units from the calculations.	Guess values of 0 with units strip the units from the calculations.	Guess values of 0 with units produced unit-balanced results.