roc

Gross rate of change pseudofunction

Syntax

roc(expression)
roc(expression, k)

Description

If the input argument k is not specified, this pseudofunction expands to

((expression)/(expression{-1}))

If the input argument k is specified, it expands to

((expression)/(expression{k}))

The time-shifted expressions, expression{-1} and expression{k}, are based on expression, and have all its time subscripts shifted by –1 or by k periods, respectively.

Examples

The following two lines

roc(z)
roc(x+y,-2)

will expand to

((Z)/(Z{-1}))
((X+Y)/(X{-2}+Y{-2}))