Surya Siddhanta
रवीन्द्वोः षड्भयुतयोः प्राग्वल् लग्नान्तरासवः। एकराशौ रवीन्द्वोश् च कार्या विवरलिप्तिकाः॥
Add six signs to the longitudes of the sun and moon respectively, and find, as in former processes, the ascensional equivalent, in respirations, of their interval (lagndntardsavas) : if the sun and moon be in the same sign, ascertain their interval in minutes.
english translation