Simcenter 3D Solutions Invalid Math Function Dimensionality

A syntax error may occur when creating a math function that refers to the dimensionality of the function, despite the function meeting other requirements. This may refer to specific constants within the function or to the function as a whole. The error will say something along the lines of "____ must have the same dimensionality" and "Math function definition is invalid".

Solution

The cause of this error is due to Motion Preference called "Math Functions Unit Policy" which may be activated by default. This option requires that all constants in a math function have a unit explicitly defined. Without this option enabled, there will be no unit check performed and the units specified for the Y-axis in the Axis Unit Setting will be applied to the resulting value. 

The math function syntax will be accepted by simply adding the units to the function after each of the constant values in square brackets. For example, the math function showed above "Step(time, 5, 1, 12, 0)" can be corrected by adding units for the time inputs and for the outputs (in this case velocity). The correct syntax for this function will be "Step(time, 5[sec], 1[m/sec], 12[sec], 0[m/sec])". In this case, the time constants have the same units in seconds and the result of the function will give the units in meters per second. Clicking the green check mark will perform a syntax check to confirm this.

This units policy does not require that the output units be exactly the same as the ones specified in the Axis Unit Setting, but it must have the same dimensionality (i.e. some form of velocity units in this case). A list of valid units for each dimension and their correct syntax can be found in the Simcenter 3D Motion documentation on Support Center: https://docs.sw.siemens.com/en-US/product/289054037/doc/PL20201029134623742.motion/html/xid1876078

This policy can be deactivated by going to File->Preferences->Motion and changing the "Math Functions Unit Policy" from "Apply Units" to "Ignore Units". 

Notes