MultiArrayUnitModel$getFitUnitGroupFunction: Static method to get the low-level function that fits the PLM
Description
Static method to get the low-level function that fits the PLM.
Any subclass model must provide this method, which should return
a function
that accepts an IxK matrix
.
Usage
## Static method (use this):
## MultiArrayUnitModel$getFitUnitGroupFunction()
## Don't use the below:
"getFitUnitGroupFunction"(...)