[TTrend,BaseDate] = dat2ttrend(Range)
[TTrend,BaseDate] = dat2ttrend(Range,BaseYear)
[TTrend,BaseDate] = dat2ttrend(Range,Obj)
Range [ numeric ] - Date range from which an integer linear time trend will be constructed.
BaseYear [ model | VAR ] - Base year that will be used to construct the time trend.
Obj [ model | VAR ] - Model or VAR object whose base year will be used to construct the time trend; if both BaseYear and Obj are omitted, the base year from irisget('baseYear') will be used.
TTrend [ numeric ] - Integer linear time trend, unique to the input date range Range and the base year.
BaseDate [ numeric ] - Base date used to normalize the input date range; see Description.
For regular date frequencies, the time trend is constructed the following way. First, a base date is created first period in the base year of a given frequency. For instance, for a quarterly input range, BaseDate = qq(baseYear,1), for a monthly input range, BaseDate == mm(baseYear,1), etc. Then, the output trend is an integer vector normalized to the base date,
TTrend = floor(Range - BaseDate);
For indeterminate date frequencies, BaseDate = 0, and the output time trend is simply the input date range.