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

379 We defined above that the angle KM̂P is Āyana Valana and the angle PM̂N as the Ākṣa-Valana. These are respectively called Bimbīya-Āyana Valana and Bimbīya-Ākṣa-Valana being subtended at M, the centre of the Bimba ie. the disc of the Moon. If in fig. 78, T be the foot of the celestial latitude of the Moon, then the respective angles KT̂P and PT̂N are called the Sthānīya- Āyana-Valana and the Sthānīya-Ākṣa-Valana ie. the angles subtended at the Sthāna or the construed position of the Moon on the ecliptic. The Āyana-Valana is zero and a minimum when M or T lies at the solstices, and a maximum equal to ω when those points lie at r or ♎. Similarly the Ākṣa- Valana is a minimum equal to zero when M or T lies on the meridian and a maximum equal to ϕ when those points lie at the east or west points. In other words the Āyana-Valana increases from zero to ω as M or T moves along the ecliptic from a solstice to an equinoctial point; and the Ākṣa-Valana increases from zero to the maxi- mum value of ϕ as M or T moves along zE or zω from z the zenith to E or ω along the prime-vertical. Hence Āyana Valana is perceived to be proportional to H sin (90+λ) where λ is the longitude of M or T, since when λ = 90, H sin (90 + 90) = 0 and when λ = 0, H sin (90+90)=0 and when λ=0, H sin (90+0)=R, a maximum; similarly the Ākṣa-Valana is perceived to be proportional to H sin z where z is the Sama-Vritta- Natāṁśa defined before, since, when z=0, M or T is at the zenith and the Ākṣa Valana is zero and when M or T is at the East or West point, z=90° and H sin z=R, a maximum. It is worth-hearing Bhāskara, at this juncture (Ref. verses 30-74 under the caption Valana Vāsanā pages 305- 306. Ānandāśrama edition of Golādhyāya Vol. 2. Poona).