Pi (letter)

From Wikinfo

Greek alphabet
Αα	Alpha	Νν	Nu
Ββ	Beta	Ξξ	Xi
Γγ	Gamma	Οο	Omicron
Δδ	Delta	Ππ	Pi
Εε	Epsilon	Ρρ	Rho
Ζζ	Zeta	Σσς	Sigma
Ηη	Eta	Ττ	Tau
Θθ	Theta	Υυ	Upsilon
Ιι	Iota	Φφ	Phi
Κκ	Kappa	Χχ	Chi
Λλ	Lambda	Ψψ	Psi
Μμ	Mu	Ωω	Omega
Obsolete letters
File:Digamma uc lc.svg	Digamma	File:Qoppa uc lc.svg	Qoppa
File:San uc lc.svg	San	File:Sampi uc lc.svg	Sampi
Other characters
File:Stigma uc lc.svg	Stigma	File:Sho uc lc.svg	Sho
File:Heta uc lc.svg	Heta
Greek diacritics

Pi (uppercase Π lowercase π), is the letter of the Greek alphabet, used to represent the "[p]" sound in Greek. In the system of Greek numerals it has a value of 80. Letters that came from it include the Roman P and Cyrillic П.

The upper-case letter Π is used as a symbol for:

• The product operator in mathematics (similar to a series).
• In textual criticism, Codex Petropolitanus, a 9th century, uncial codex of the Gospels, now located in St. Petersburg, Russia.

The lower-case letter π is used as a symbol for:

• The mathematical constant π ≈ 3.14159, the ratio of a circle's circumference to its diameter.
• The prime counting function in mathematics.
• The pi mesons in particle physics.
• Profit in microeconomics.
• Inflation rate in macroeconomics.

References

• Adapted from the Wikipedia article, "Pi_(letter)" http://en.wikipedia.org/wiki/Pi_(letter), used under the GNU Free Documentation License