Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 1 · Basics and Panchanga
ज्योतिषमूलं पञ्चाङ्गं च
विपटीतायनगतौ चंद्रार्कौ क्रांतिलिप्तिकाः ।समास्तदा व्यतीपातो भगणार्द्धे तपोयुतौ ॥ १७५ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 54, verse 175.
Say the Moon and Sun are on opposite courses. Their declinations are equal in minutes. Their sum is half a circle. Then it is Vyatipata (a bad Sun and Moon yoga).
Simple meaning: When the Sun and Moon are on opposite courses with equal declinations, Vyatipata occurs.
भास्करेंद्वोर्भचक्रांतचक्रार्द्धावधिसंस्थयोः ।
When the Sun and Moon together are near 360 or 180 degrees, find each one's declination.
अथोजपदगम्येंदोः क्रांतिर्विक्षेपसंस्कृता ।
Correct the Moon's declination by its latitude. If it is greater than the Sun's, the point has passed.
न्यूना चेत्स्यात्तदा भावी वामं युग्मपदस्य च ।
If it is less, the point is still to come. The even quarter works the other way.