# Upsilon

Upsilon (uppercase/lowercase Υ υ) is the 20th letter of the Greek alphabet. It is used to represent the "u" sound in Ancient Greek and "i" in Modern Greek. In the system of Greek numerals, it has a value of 400. Letters that came from it include the Roman U, V and Y, and the Cyrillic У.

In mathematics, the uppercase ${\displaystyle \Upsilon }$ is used to represent the upsilon function (a variant of Riemann zeta function), while the lowercase ${\displaystyle \upsilon }$ is used as a general variable.[1] In physics, the uppercase ${\displaystyle \Upsilon }$ is used to represent an upsilon meson. In astrology, the same letter is used for the sign of Aries.[2]

## References

1. "Greek/Hebrew/Latin-based Symbols in Mathematics". Math Vault. 2020-03-20. Retrieved 2020-10-07.
2. "Upsilon Symbol in Greek Alphabet". www.greeksymbols.net. Retrieved 2020-10-07.