Surya Siddhanta
अर्काग्रा स्वेष्टकर्णघ्नी मध्यकर्णोद्धृता स्वका । विषुवद्भायुतार्काग्रा याम्ये स्याद् उत्तरो भुजः॥
To this reduced sine of the Sun's amplitude add the equinoctial shadow; the sum will be the north Bhuja (of the shadow at the given time) when the Sun is in the southern hemisphere, but when he is in the northern hemisphere, take the reduced sine of amplitude from the equinoctial shadow, and the remainder will be the north Bhuja.
english translation
arkAgrA sveSTakarNaghnI madhyakarNoddhRtA svakA । viSuvadbhAyutArkAgrA yAmye syAd uttaro bhujaH॥
hk transliteration by Sanscript