How to decide what intonation system to use on violin

This video explains how to decide what system of intonation to use when on the violin. Use Pythagorean Intonation most of the time, particularly for all melodies, scales, and arpeggios. Use Just Intonation for double stops and for chords in string quartets. Pianos are tuned in equal temperament. Violinists should only adjust to piano pitches if both instruments are playing the same pitch for a long duration.