Hello!
I am trying to create a new unit and having a little trouble with quantity based calculation.
I have created a new unit set entitled "ICE Engines" to deal with units specific to internal combustion engines. The first unit I am working with relates to spark advance. Some systems report spark as degrees before TDC (Deg_BTDC), and some report spark as degrees AFTER TDC. So, these are the same measurement, just opposite signs.
I have created a new quantity called TDC Relative with dimensions 0,0,0,0,0,0,0 and category of rotation, since deg_BTDC is just degrees, but in a relative sense.
For the units the factor for Deg_ATDC is 1 and Deg_BTDC is -1. This enables the unit conversion to work great, so I can easily convert from Deg_BTDC to Deg_ATDC. This is wonderful.
The problem I run into is when I add two of these together in a quantity based calculation. If I subtract 1 Deg_BTDC from -1 Deg_ATDC, I get 0, as I expect, BUT the unit is in Radians, I assume because of the category of rotation. This is really ok, except that I cannot convert Radians back to Deg_BTDC.
If I remove the category of rotation, I again get the correct numeric value, but the unit is "1", so that doesn't work either.
So, how do I do one (or both) of the following: Create a unit set that allows quantity based calcultions to result in a unit the new set, or convert a default unit (Radians) into a custom created unit?
