Store factor names in the factorial.plan object, as a list within the
factor.names attribute.
Usage
fp_add_names(dm, ...)
Value
the design matrix with the named factors.
Arguments
dm
the design matrix.
...
a set of factors to name, with their respective names, e.g.
A="Temperature", B="Pressure". If the factor is not in the design matrix
factors list, a warning is printed and the factor is skipped.