Phaladeepika
धूमो वेदगृहैस्त्रयोदशभिरप्यंशैः समेते रवौ स्यात्तस्मिन् व्यतिपातको विगलिते चक्रादथास्मि न्युते । षड्भिभैः परिवेश इन्द्रधनुरित्यस्मिंश्च्युते मण्डला- दत्यष्टयंशयुतेऽत्र केतुरथ तत्रैकर्क्षयुक्तो रविः ॥ ५॥
The position of Dhuma is found by adding 4 signs, 13' 20' to the figures for the Sun. If you subtract Dhuma from 12 signs, the result will indicate the figures for Vyatipata. This increased by six signs becomes Parivesha or Paridhi. When Parivesha again is subtracted from 12 signs, we get Indra chapa. Add to this 16' 40 ; Kethu is obtained. Kethu increased by ono sign will give the figures for the Sun.
english translation
dhUmo vedagRhaistrayodazabhirapyaMzaiH samete ravau syAttasmin vyatipAtako vigalite cakrAdathAsmi nyute । SaDbhibhaiH pariveza indradhanurityasmiMzcyute maNDalA- datyaSTayaMzayute'tra keturatha tatraikarkSayukto raviH ॥ 5॥
hk transliteration by Sanscript