Surya Siddhanta
तच्चापम् भादिकम् क्षेत्रम् पदैस् तत्र भवो रविः। इष्टे +अह्नि मध्ये प्राक्पश्चाद् धृते बाहुत्रयान्तरे ॥
On any day place a vertical gnomon on an horizontal plane; mark the end of the shadow at three different times on the plane, and describe a circle passing through these points. Then the end of the shadow of that gnomon will revolve in the circumference of this circle through that day.[2] [2. This Rule is refuted by Bháskaráchárya in his Goladhyáya, and he is right, because the end of the gnomonical shadow revolves in an hyperbola in the places between the arctic and antarctic circles. B. D.]
english translation
taccApam bhAdikam kSetram padais tatra bhavo raviH। iSTe +ahni madhye prAkpazcAd dhRte bAhutrayAntare ॥
hk transliteration by Sanscript