Surya Siddhanta
लम्बज्यार्कगुणाक्षज्या विषुवद्भाथ लम्बया । स्वाक्षार्कनतभागानाम् दिक्साम्ये +अन्तरम् अन्यथा ॥
Find the difference between the degrees of the latitude (at a given place) and those of the Sun's zenith distance at noon when they are both of the same name, but when they are of contrary names find the sum of them; the result will be the Sun's declination; multiply its sine by the Radius.
english translation
lambajyArkaguNAkSajyA viSuvadbhAtha lambayA । svAkSArkanatabhAgAnAm diksAmye +antaram anyathA ॥
hk transliteration by Sanscript