Surya Siddhanta
ग्राह्यग्राहकयोगार्धाच् छोध्याः स्वच्छन्नलिप्तिकाः। ताद्वर्गात् प्रोज्झ्य तत्कालविक्षेपस्य कृतिम् पदम्॥
Subtract the minutes contained in the given eclipsed part from half the sum of the diameter of that which is covered and that which is the coveror; from the square of the remainder subtract the square of the Moon's latitude at that time.
english translation
grAhyagrAhakayogArdhAc chodhyAH svacchannaliptikAH। tAdvargAt projjhya tatkAlavikSepasya kRtim padam॥
hk transliteration by Sanscript