सिद्धान्तशिरोमणि: गणिताध्याय (भास्कराचार्य - ग्रहगणित, मध्यमाधिकार व स्पष्टाधिकार सटीक)

170 the case of the Inferior planets, the Sighraphala will be itself their elongation eastern or western. Then they rise in the West, being near Superior conjunction. When again their Sighra anomalies equal respectively 155° and 177°, the same Sighraphalas will arise so that they set heliacally in the West. Then as the Sighra anomalies attain the symmetrical values on the other side ie. (360- 155) and (360-177) ie. 205° and 183° the Sighraphalas being the same, they rise in the East. Again when they attain the values (360-50) and (360-24) ie. 310° and 336°, they set in the East on account of the same Sighraphalas or Kālāmsas. Verse 44. When the Sighra anomalies have parti- cular values, to decide when the planets rise or set helia- cally, we have to take the difference of those particular values and the numbers given above for the respective Sighra anomalies, convert them into minutes of arc and divide the results by the daily motion in the Sighra ano- malies in minutes of arc. Then we have the number of days in which the rising or setting takes place thereafter. Comm. Suppose it is required when Mercury rises in the West. Suppose we want to compute this on a parti- cular day when Mercury's Sighra anomaly is x°. Then because we know that Mercury rises in the West when his Sighra anomaly is 50, we have to calculate by how many days the difference | x-50 | of the Sighra anomaly would be covered. Let the daily motion of the Sighra anomaly be y' per day, Then by rule of three (| x-50 | × 60) / y will be the number of days before or after as the case may be for Mercury to rise in the West. Verse 45. To obtain the Mean planet knowing the True. Assume the True planet to be the Mean; compute the Manda and Sighraphalas and applying them inversely,