Surya Siddhanta
विषुवत्याम् विशोध्योदग्गोले स्याद् बाहुर् उत्तरः । विपर्ययाद् भुजो याम्यो भवेत् प्राच्यपरान्तरे ॥
In the latter case, when the reduced sine of amplitude ia greater than the equinoctial shadow, subtract this shadow from the reduced sine; the remainder will be the south Bhuja between east and west line and the end of the shadow at the given time. Every day the Bhuja at noon equals the Gnomon's shadow at that time.
english translation
viSuvatyAm vizodhyodaggole syAd bAhur uttaraH । viparyayAd bhujo yAmyo bhavet prAcyaparAntare ॥
hk transliteration by Sanscript