fractional change of a quantity

A term which may be expressed infinitesimally at time $t$ by the differential $d Q t Q t$ . For a finite time interval the quotient is

$Δ Q t 1 t 2 Q t 1 = Q t 2 − Q t 1 Q t 1$

The quantities $Q t 1$ and $Q t 2$ are of the same kind and have the same type of component. Fractional change has dimension one. Examples are: mass fractional change, $d m t m t$ ; amount of substance fractional change, $d n t n t$ .

Source:

PAC, 1992, 64, 1569 (Quantities and units for metabolic processes as a function of time (IUPAC Recommendations 1992)) on page 1571