Calculation of the Ascendant and Houses

When the calculation of the forward Ascendant Dhana-lagna: a method of calculating the rising sign by moving forward from the Sun's position is performed, the portion of the zodiac sign yet to be traversed (bhogya) should be taken. Multiply this by the local rising time of that specific sign (svodaya) and divide by thirty. The result—whether it be the Sun’s traversed or remaining portion—should be subtracted or cleared from the desired time Ishta-ghati: the time elapsed from sunrise to the moment of the event in ghatikas and palas 1 ghatika = 24 minutes; 1 pala = 24 seconds.

After that, from the remainder, one should subtract the rising times of the signs yet to come. Specifically: when the "past time" is being calculated, the preceding rising times are subtracted from the multiplied rising time. When the "future time" is being calculated, the subsequent rising times are subtracted. The remainder is then multiplied by thirty original: "kha-agni" (literally 'space-fire' representing 0 and 3, or 30) and divided by the "incomplete" rising time Ashuddhodaya: the rising time of a sign that cannot be fully subtracted from the remaining time. The resulting degrees and minutes should be recorded. This value is then subtracted from a sign that was not fully cleared, or added to a sign that was fully cleared.

In this way, for both the backward calculation Rina-lagna and the forward calculation Dhana-lagna, based on the count starting from Aries original: "Mesha", the degrees and minutes are adjusted within the sign corresponding to the incomplete rising time. Then, the precession of the equinoxes Ayanamsha: the longitudinal difference between the tropical and sidereal zodiacs, necessary for precise calculations must be applied.

From the desired nadis another term for ghatika and palas, and from the past or future local rising times: [22]
The remainder, multiplied by thirty and divided by the "incomplete" rising time, gives the degrees and minutes.
Subtract or add this to the "incomplete" or "pure" sign, and apply the precession. [23]
Similarly, using the equatorial rising times (Lankodaya), the traversed or remaining portions of the Sun are to be subtracted from the time converted to palas.
The tenth house Dashama-bhava: the Midheaven or the highest point in the sky at the moment of the event is found from the east or west hour angle, just as before. [24]
Adding six signs to the Ascendant gives the seventh house Jaya-bhava: the western horizon or descendant; adding six signs to the tenth gives the fourth house Turya-bhava: the lowest point or Nadir. [25]
The next six houses are also found by adding six signs to the first six. When a planet's position equals the house center, its influence is full; when it equals the junction (sandhi) between houses, its influence is zero. [26]

By this method, the Ascendant (Lagna) The sign rising on the eastern horizon is established. Following this logic, by using the equatorial rising times (Lankodaya), the Sun's traversed and remaining portions are calculated. This is subtracted from the time converted to palas. The rest of the procedure to find the tenth house is the same as described before.

Specifically: when the hour angle is in the east (purva-nata), treat that eastern angle as the desired time, calculate using equatorial rising times, and subtract the Sun's traversed portion; the remaining steps are like the backward calculation. When the hour angle is in the west (pashchima-nata), treat that western angle as the desired time, use equatorial rising times, and subtract the Sun's remaining portion; the remaining steps are like the forward calculation. This results in the tenth house.

Having explained the Ascendant and the tenth house, the author now explains how to find the other houses: By adding six signs (sapaddhe). By adding six signs to the Ascendant, the seventh house is found. Similarly, by adding six signs to the tenth house, the fourth house is found. Thus, the four cardinal houses are established. Then, subtract the Ascendant from the fourth house; divide the remainder by six to find the "house-sixth" portion. This portion is added to the Ascendant...

Technical