I've realised that add_time_to_date doesn't take into account whether we are at the beginning of the year. For example, if I pass the following parameter to the function:
CALL FUNCTION 'ADD_TIME_TO_DATE' "
i_idate = '20130101'
i_time = '-1'
i_iprkz = '2'
o_idate = " sy-datum
I get the value 01.00.2013.
Can anybody help me or give another function which works in this case?
Thanks in advance.