Aṁśaka Āyurdaya
There are two primary calculation methods (1) Sāmānya-anugata and (2) Prākrama-anugata. Further, the basic calculation gets modified by reductions (haraṇa) and increase (bharaṇa) which is either (a) kṛta vṛddhikā (allowed modifications) or (b) ākṛta vṛddhikā (modifications disallowed). In this manner we can have four separate results. Maharṣi Parāśara uses the kṛta vṛddhikā and allows both reduction and increase called haraṇa bharaṇa respectively.