Phaladeepika
स्वोच्चे पूर्णं स्वत्रिकोणे त्रिपादं स्वक्षेत्रऽर्द्धं मित्रभे पाद्दमव । द्विट्क्षेत्रेऽल्पं नीचगेऽस्तं गतेऽपि क्षेत्रं वीर्यं निष्फलं स्याद् ग्रहानाम् ॥ ७॥
A planet gets one full Rupa as positional strength when he is in his exaltation Rasi. The strength is 3/4 when he is posited in his Moolatrikona Rasi. It is 1/2 when the planet occupies his own Rasi. When the planet is in a friendly house, his bala is only 1/4. In an inimical house, he gets only very little. The strength is nil when he is in his depression sign or eclipsed by the Sun's rays.
english translation
svocce pUrNaM svatrikoNe tripAdaM svakSetra'rddhaM mitrabhe pAddamava । dviTkSetre'lpaM nIcage'staM gate'pi kSetraM vIryaM niSphalaM syAd grahAnAm ॥ 7॥
hk transliteration by Sanscript