Calendar duration in quarters
Q = calquarters( returns
an array representing calendar quarters equivalent to the values in
array X)X.
If X is a numeric array, then Q is
a calendarDuration array with each element equal
to the number of calendar quarters in the corresponding element of X.
If X is a calendarDuration array,
then Q is a double array with
each element equal to the number of whole calendar quarters in the
corresponding element of X.
Q = fix(calmonths(t)/3)