Mathcad 13 features a number of improvements to promote worksheet quality, increase calculation speed, and provide traceability. In some cases, these changes have caused incompatibilities with previous versions. In most cases, they provide clearer, faster, or more stable ways of achieving the same functionality. For complete information on these changes, see the Migration Guide Tutorial included with the product.

Feature	Mathcad 13	Mathcad 12	Mathcad 11
Functions That Don't Unit Balance Throw an Error When Defined	Functions return unit errors when defined.	Functions return unit errors when defined.	Functions return unit errors when evaluated.
Functions Valid Only for Unitless Arguments	Functions must return units depending only on the units of the inputs.	Functions must return units depending only on the units of the inputs.	Functions can conditionally return results of different units depending on input values.
Exponentiation and Differentiation Operators need Explicit Power and Order with United Arguments	United values can be raised to an explicit numeric power.	United values can be raised to an explicit numeric power.	United values can be raised to a variable power.
2D Plots Require Matching Units in Axes and Markers	Axis limits and markers in 2D plots are required to have the same units.	Axis limits and markers in 2D plots can have mismatched units.	Axis limits and markers in 2D plots can have mismatched units