.BG
.FN time
.FN cycle
.TL
Create Time Vector
.CS
time(x)
cycle(x)
.AG x
time-series.  Missing values (`NA's) are allowed.
.RT
time-series with same `start', `end' and `frequency' as `x'.
`time' returns  the time value at each point, e.g., the
value at January, 1973 is 1973.0, and the value at July 1973 is
1973.5.

`cycle' returns the position of
each observation within the cycle associated with the series.
If `x' were monthly, this would be the month number: 1 for each January, etc.
.EX
cgrowth <- code(cycle(growth), 1:12, month.name)
tapply(growth, cgrowth, mean)   # mean growth for each month
.KW ts
.WR
