There are five angams (parts) is called as
panjangam and its parts.
There are two type of panjangams Drik or
Thirukkanita and Vakya, and many types of "Ayanamsa" which is very hard to
understand now, but which plays a key role in making a panjangam.
Vakya
method is very old type, which depends on the "Slokas" which is also called
'Vakyams' in which every aspect of the panjangam has been given as formula.
These formulae are like some algebraic expressions (a+b)2 (square) can be
expanded as a2 + b2 + 2ab, this is only example.
Like that, those slokas
will be memorized by the astrologers and some simple additions and subtractions
to the expansion of that slokas will derive every aspect of the panjangam for
that specific year.
It is obvious, by which these 'Vakyas' we can not get
the perfect calculations out of it.
So, as a result, the Vakya Panjangams
are 'Approximations'. But, it includes some sutras to adjust and get more
or less perfect things in every small intervals.
Now the Thirukkanita
panjangam has complete calculations, which may or may not require ephemeris.
These calculations are made with two to eight digit after a period (point / dot)
to get the value of fractions.
So, there must be difference in Vakyam
and Thirukkanitham.
As per my experience and from our elders' advise,
using Thirukkanitham is better for the purpose of astrological
predictions.
And, Using 'Vakyam' is better for the purposes of
'Anushtanam'. Because in Thirukkanitha panjangam they have no provision to
decide a ritual according to shastrams. For example, there is some sukshmam to
find on which day the 'Vaishnava Ekadasi', on which day the 'shradham' should be
done for a specific Thithi etc.
Needless to say, our Paranthaman
panjangam is "Vaakyam" which is puplished for the purpose of
Anushtanam.
I know that the explanation given may clear the doubt for
somebody, and it may further confuse somebody.
Though I can explain more
about panjangams,
I do not wish to continue on this subject more for time
being.
nvs