Surya Siddhanta
भुक्त्यन्तरेण विभजेद् अनुलोमविलोमयोः। द्वयोर् वक्रिण्य् अथैकस्मिन् भुक्तियोगेन भाजयेत्॥
And divide the products by the difference of daily motions, if both are moving with direct, or both with retrograde, motion : if one is retrograding, divide by the sum of daily motions.
english translation
bhuktyantareNa vibhajed anulomavilomayoH। dvayor vakriNy athaikasmin bhuktiyogena bhAjayet॥
hk transliteration by Sanscript