Surya Siddhanta
लब्धम् प्राच्याम् ऋणम् सौम्याद् विक्षेपात् पश्चिमे धनम् । दक्षिणे प्राक्कपाले स्वम् पश्चिमे तु तथा क्षमः॥
The result, when latitude is north, is subtractive in the eastern hemisphere, and additive in the western ; when latitude is soitth, on the other hand, it is additive in the eastern hemisphere, and likewise subtractive in the western.
english translation
labdham prAcyAm RNam saumyAd vikSepAt pazcime dhanam । dakSiNe prAkkapAle svam pazcime tu tathA kSamaH॥
hk transliteration by Sanscript