The per-size factor is found in either of the two spellings mizer uses for
it, 1/g and g^-1, and is then swapped for the size unit of the target
measure. A density per logarithmic size carries no size unit at all — a
number per log weight interval is just a number — so converting to one
removes the factor instead: 1/g becomes dimensionless and g^-1/year
becomes 1/year.
convert_density_units(units, from, to)The units expressed in the to measure.
The units of the values, possibly NULL.
Density measures, see density_measures.
Units that state no per-size factor are returned unchanged, since there is then nothing to identify as the size unit.