[OPE-L:7017] [OPE-L:509] Time subscripts postscript [ope 506]

Alan Freeman (a.freeman@greenwich.ac.uk)
Thu, 25 Feb 1999 13:07:28 +0000

Gerald Levy wrote:

> I wonder: when was the use of time subscripts in equations first
> introduced? (Paul C?) Was it being used by mathematicians in Marx's
> time?

Marx credits Sismondi with the introduction of period analysis, and
generally considers that the physiocrats applied it well to the study of

Sowell also credits Sismondi with the introduction of period analysis.

Period analysis is where time makes its appearance in both the classical
treatment and Marx's treatment. Just because Marx uses C and C' to refer to
two points in time, instead of the more modern time subscript, doesn't make
it any the less a temporal treatment. C is at one time and C' is at a
succeeding time.

I think you'll find Marx's usage quite common among the mathematicians of
the day and generally in the calculus; I believe you'll find it in Newton,
for example, though I'll have to go back and check the text.