expand an annual series into a quarterly one
tsout=a2q(tsin)
* tsin = an annual time series
* option = an integer, between -1 and 3:
. -1 if each quarterly value is equal to the annual one (default if the argument is not given)
. 0 if each quarterly value is equal to the annual one divided by 4
. n if the value of the n-th month is equal to the annual one and the others are set to %nan
* tsout = the corresponding quarterly time series
x = reshape([1:35],'1978a') // create an annual ts y = a2q(x) // gives an montly ts, from 1978q1 to 2012q4 with values 1 for all quarters of year 1978, // 2 for all quarters of year 1979... y = a2q(x,4) // gives a quarterly ts from 1978q1 to 2012q4 with %nan values for all quarters except the last one of the year // and 1 for the 4-th quarter of 1978, 2 for December 1976... |  |  |