expand an annual series into a monthly one
tsout=a2m(tsin,option)
* tsin = an annual time series
* option = an integer, between -1 and 12:
. -1 if each monthly value is equal to the annual one (default if the argument is not given)
. 0 if each monthly value is equal to the annual one divided by 12
. 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 monthly time series
x = reshape([1:35],'1978a') // create an annual ts y = a2m(x) // gives an montly ts, from 1978m1 to 2012m12 with values 1 for all months of year 1978, // 2 for all months of year 1979... y = a2m(x,12) // gives a monthly ts from 1978m1 to 2012m12 with %nan values for all non December months // and 1 for December 1978, 2 for December 1976... |  |  |