Mathematical Astrology Part II
Astrology, cognised by the Seers in altered states of Consciousness, became a boon to humanity with the result its believers number more than 1 billion. Like a Lamp Divine which shineth in the darkness illuminating all effects & all causes, Astrology remains as one of the noblest professions & one of the greatest sciences which the human intellect has built up ! Related to Astronomy & Mathematics, Mathematical Astrology is as important as Predictive Astrology, as without its mathematical base, prognostication is not just possible.
Strength based on Even & Odd Signs ( Ojayugmarasyamsa Bala )
Strength acquired by the tenancy of Even & Odd Zodiacal Signs in both Rasi ( D1 ) & Amsa ( D9 ) is called as Ojayugmarasyamsa Bala. Certain planets acquire strength in Odd Signs while others gets strengthened in Even Signs. Certain mathematical values are assigned to planets who become powerful in Odd or Even Signs.
The values given are in 1/60 Units called Shashtiamsas. Luna ( Moon ) & Dione ( Venus ) in even Signs in both D1 ( Rasi ) or D9 ( Amsa ) attain a strength of 15 Shashtiamsas. On the contrary, in odd Signs Sol ( Sun) , the Fiery Planet ( Mars) , Jove ( Jupiter ) , Woten ( Mercury) & Chronos ( Saturn ) get a strength of a similar value ( in both Rasi & Amsa ).
The Moon in an Even Rasi & an Even Navamsa acquires a strength of 15 + 15 = 30 Shashtiamsas.
Hence we call this as Ojayugmarasyamsa Bala.

Quadrants or Angles ( Kendras )
1,4,7 & 10 Houses are called angles as they form a Rectangle. Angular lords means the lords of these houses. Angular Jupiter means Jove in these houses.
Opinions differ as to what Angles are. Some scholars take this as 1,4,7 & 10 Rasis while others take them to be the 1,4,7 & 10 Houses or Bhavas. ( Some follow the Rasi Theory & others the Bhava Theory ). Parasara follows the Rasi Theory while Balabhadra, the author of Horarathna ( The Jewel of Time ) favours the Bhava Theory. We here intend to follow the Parasarian view.
Kendras  1,4,7 & 10 Signs 
Panaparas  2nd, 5th, 8th & 11th Signs 
Apoklimas  3, 6,9 & 12th Signs 
Panaparas These are the signs next to Angles. They are the 2nd, 5th, 8th & 11th.
Apoklimas These are the next signs to Panaparas. They are the 3, 6,9 and 12th
Angular Strength ( Kendra Bala )
Angular Strength is the strength acquired by planets in an angle which is 60 Shashtiamsas; whereas they get 30 in a Panapara & 15 in an Apoklima. This must be considered only in the D1 or the Rasi Chart.

Decanate Strength
Planets are divided into Masculine, Feminine & Hermaphrodite ones.
Masculine Planets  Sun, Jupiter & Mars 
Hermaphrodite Planets  Saturn & Mercury 
Female Planets  Moon & Venus 
A male planet in the first Drekkana = 15 Shashtiamsas
A Hermaphrodite planet in the middle Drekkana = 15 Shashtiamsas
& a Feminine planet in the last Drekkana = 15 Shashtiamsas
Total Positional Strength ( Sthana Bala )
The sum of all the five subdivisions worked above added together will give the Total Positional Strength of planets.
Positional Strength = Exaltation Strength + Sevenfold Division Strength + Odd & Even Strength + Angular Strength + Decanate Strength
In Sanskrit
Sthana Bala = Oocha Bala + Saptavargaja Bala + Ojayugmarasyamsa Bala + Kendra Bala + Drekkana Bala
Directional Strength ( Dig Bala )
Planets in certain directions become powerful and this is called Dig Bala or Directional strength.
Dik or Direction
Ascendant  First House  East 
Descendant  Seventh House  West 
Zenith  Tenth House  South 
Nadir  Fourth House  North 
Planets & Direction ( Dik )
Numerical values are assigned to planets in certain directions. For instance Jupiter & Mercury become powerful when they are in the Ascendant ( East ). Sun & Mars are powerful on the Upper Meridien or Zenith ( Tenth ). Saturn is powerful in the West ( Seventh ) & Moon & Venus become potent on the Nadir ( Fourth ). They will have complete Directional strength or Digbala ( 60 Shashtiamsas ) in these directions.
Directional Arc  ( Digbala Arc )
On the contrary, there are certain powerless points which when tenanted by planets are Zero Directional strength or Digbala. Sun gets full Directional Strength of 60 Shashtiamsas when in the South or Tenth. But his Digbala is Zero when he is 180 degrees away from that point, viz North. In other words. the Arc of the Ecliptic between the longitude of a planet and its powerless point, is known as the Digbala Arc.
So there are powerful & powerless points for a planet on the Zodiac & when a planet approaches its powerful point, it gains Digbala & when it reaches the powerless point it gradually loses Digbala.
According to Parasara, the father of Vedic Predictive Astrology, the longitude of the 4th house is to be deducted from the longitudes of the Sun & Mars. The longitude of the 7th House is to be subtracted from Jupiter's & Mercury's longitudes. The 10th House longitude is to be subtracted from the longitudes of Venus & Moon & Ascendant's from Saturn's. If the difference exceeds 180 degrees, subtract it from 360 degrees.
The result is Directional Arc ( Digbala Arc )
Directional Arc ( Digbala Arc ) = Planet's longitude  its Powerless Cardinal Point.
If difference is more than 180 degrees subtract it from 360 degrees.
So we find that Mathematical Astrology is not as easy as Predictive Astrology, as many suppose !