Published online by Cambridge University Press: 18 August 2016
The Calculus of Differences is a somewhat extensive subject, but it is not necessary now to go far into it, or to occupy ourselves with its application to other than the simplest class of functions, namely, rational, algebraical, and integer functions. The theorems we require might have been left to be deduced as occasion for them should arise; but it has been thought better— and the arrangement will certainly be more convenient for reference—to bring the greater portion of them together in this place.
page 154 note * The symbol (—1)n is a convenient substitute for the periphrasis, “plus or minus according as n is even or odd.” And, in like manner, (−1) n+1 expresses, “plus or minus according as n is odd or even.”