144 TRUB LONGITUDE OF A PLANET When the true-mean planet is in the second quadrant, true longitude longitude of the sighrocca (180° - spasta-bhuja). When the true-mean planet is in the third quadrant, true longitude=longitude of the sighrocca - (180°+spasta-bhuja). When the true-mean planet is in the fourth quadrant, true longitude-longitude of the sighrocca - (360° - spasta-bhuja). The spasta-bhuja due to the sighrocca is determined by the formula: SB X ER Rsin (spasta-bhuja)= ET Rsin X R H' - where is the bahu (due to the sighrakendra), R the radius, and H' the distance ET of the true planet, called sighrakarna. A rule for finding the mandakarna and sighrakarna: 47. Multiply the radius by the (planet's) corrected epicycle and then divide (the product) by 80; then subtract the quotient from or add that to the Rsine of the corresponding koti (due to the kendra) in accordance with the quadrant (of the kendra) : and then calculate the (planet's) karna as before. This method is analogous to that stated for the Sun and Moon in stanzas 19-20. The important thing to be noted is that in finding the manda- karna we have to apply the method of successive approximations as in the case of the Sun and Moon, whereas in finding the sighrakarna we have to apply the method only once.¹ The reason for this difference must have become clear to the reader from the epicyclic and eccentric theories, which have been explained above in detail. Procedure to be adopted for finding the true longitude of the planets under the eccentric theory: 48-54. Add half the difference between the (mean) planet corrected by the mandocca operation and the mean planet to or subtract that from the mean planet according as the (mean) planet as corrected for the mandocca operation is greater or less (than the mean planet). (The planet thus obtained is call- ¹ See infra, stanza $5...
