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

154 this in the original mean planet and again correcting for Sīghraphala and repeating the process till a constant value is obtained, the true planet is had with respect to the star- planets other than Mars. But with respect to Mars, let first the mean planet be corrected for half of the equation of centre. Then make half of the correction of Sīghraphala. Take the resulting planet to be the mean planet and again finding the equation of centre, make this whole correction in the original mean planet. Again taking the resulting planet to be the Mandasphuta effect the entire Sīghraphala. Then we have the true planet. Comm. The Suryasiddhānta stipulates the same kind of correction in the case of all the star-planets. "शैघ्र्यं मान्दं पुनः मान्दं शैघ्र्यं चेति चातुर्विधं, कर्तव्यं हि कुजादीनां स्फुटत्वे कर्म सूरिभिः। शैघ्र्यं फलार्धं प्रथमं ततो मन्दार्धमेव च, पश्चान्मान्दफलं सर्वं तद्वत् शीघ्रफलं ग्रहे ॥" i.e. In the first place half of the Sīghra- phala is to be effected in the mean planet; taking that to be the mean planet and computing the equation of centre half of it is administered; taking the resulting to be the mean planet and computing the equation of centre, the entire equation of centre is now to be administered in the original mean planet; taking the result to be the Manda- sphutagraha, and computing the Sīghraphala, it is to be administered in full in the Mandasphuta. Then we have the true planet. In modern astronomy, the equation of centre is first done and the result will be the planet in its heliocentric elliptic orbit. To reduce it to the geocentric position, the second correction is made which corresponds to the Hindu Sīghraphala. Thus the two corrections administered suc- cessively gives the apparent or true geocentric planet. Though the mutual relationship as conceived between the equation of centre and the Sīghraphala in Hindu Astro- nomy is deemed irrational by modern interpreters of Hindu Astronomy, there is some rationale in the process as ex-