Pi (letter)

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## Uppercase Pi

## Lowercase Pi

## History

## Variant pi

## Character encodings

### Character encodings tables

## See also

## References

This article uses material from the Wikipedia page available here. It is released under the Creative Commons Attribution-Share-Alike License 3.0.

Pi Letter

**Pi** (uppercase **?**, lowercase **?** and **?**; Greek: [pi]) is the sixteenth letter of the Greek alphabet, representing the sound [p]. In the system of Greek numerals it has a value of 80. It was derived from the Phoenician letter Pe (). Letters that arose from pi include Latin P, Cyrillic Pe (?, ?), Coptic pi (?, ?), and Gothic pairthra (?).

The uppercase letter ? is used as a symbol for:

- In textual criticism,
*Codex Petropolitanus*, a 9th-century uncial codex of the Gospels, now located in St. Petersburg, Russia. - In legal shorthand, it represents a plaintiff.

- The product operator in mathematics, indicated with capital pi notation ? (in analogy to the use of the capital Sigma ? as summation symbol).
- The osmotic pressure in chemistry.
- The viscous stress tensor in continuum mechanics and fluid dynamics.

The lowercase letter ? is used as a symbol for:

- The mathematical real transcendental (and thus irrational) constant ? ? 3.14159..., the ratio of a circle's circumference to its diameter in Euclidean geometry. The letter "?" is the first letter of the Greek words ? 'periphery' and ? 'perimeter', i.e. the circumference.
- The prime-counting function in mathematics.
- Homotopy groups in algebraic topology.
- Dimensionless parameters constructed using the Buckingham ? theorem of dimensional analysis.
- The hadron called the pion (pi meson).
- Economic profit in microeconomics.
- Inflation rate in macroeconomics.
- A type of chemical bond in which the p orbitals overlap, called a pi bond.
- The natural projection on the tangent bundle on a manifold.
- The unary operation of projection in relational algebra.
- Policy in reinforcement learning.
- Polyamory
^{[1]}

An early form of pi was , appearing almost like a gamma with a hook.

**Variant pi** or "pomega" ( or ?) is a glyph variant of lowercase pi sometimes used in technical contexts. It resembles a lowercase omega with a macron, though historically it is simply a cursive form of pi, with its legs bent inward to meet. It was also used in the minuscule script. It is a symbol for:

- Angular frequency of a wave in fluid dynamics (angular frequency is usually represented by but this may be confused with vorticity in a fluid dynamics context).
- Longitude of pericenter in celestial mechanics.
^{[2]} - Comoving distance in cosmology.
^{[3]} - Single-scattering albedo in radiative transfer.
- Mean fitness of a population in biology.
- Fundamental weights of a representation (probably to better distinguish from elements of the Weyl group, than the usual notation ).

The various forms of pi are present in Unicode as:

- Π GREEK CAPITAL LETTER PI (HTML
`Π`

**·**`Π`

) - π GREEK SMALL LETTER PI (HTML
`π`

**·**`π`

) - ϖ GREEK PI SYMBOL (HTML
`ϖ`

**·**`ϖ, ϖ`

) - ∏ N-ARY PRODUCT (HTML
`∏`

**·**`∏, ∏`

) - ᴨ GREEK LETTER SMALL CAPITAL PI (HTML
`ᴨ`

) - 𝜋 MATHEMATICAL ITALIC SMALL PI (HTML
`𝜋`

) - 𝛑 MATHEMATICAL BOLD SMALL PI (HTML
`𝛑`

).^{[4]}

- Greek / Coptic Pi
^{[5]}

Preview | Π | π | ϖ | Ⲡ | ⲡ | |||||
---|---|---|---|---|---|---|---|---|---|---|

Unicode name |
GREEK CAPITAL LETTER PI | GREEK SMALL LETTER PI | GREEK PI SYMBOL | COPTIC CAPITAL LETTER PI | COPTIC SMALL LETTER PI | |||||

Encodings | decimal | hex | decimal | hex | decimal | hex | decimal | hex | decimal | hex |

Unicode | 928 | U+03A0 | 960 | U+03C0 | 982 | U+03D6 | 11424 | U+2CA0 | 11425 | U+2CA1 |

UTF-8 | 206 160 | CE A0 | 207 128 | CF 80 | 207 150 | CF 96 | 226 178 160 | E2 B2 A0 | 226 178 161 | E2 B2 A1 |

Numeric character reference | Π |
Π |
π |
π |
ϖ |
ϖ |
Ⲡ |
Ⲡ |
ⲡ |
ⲡ |

Named character reference | Π | π | ϖ, ϖ | |||||||

DOS Greek | 143 | 8F | 167 | A7 | ||||||

DOS Greek-2 | 198 | C6 | 234 | EA | ||||||

Windows 1253 | 208 | D0 | 240 | F0 | ||||||

TeX | \Pi | \pi | \varpi |

- Mathematical Pi

Preview | ∏ | ∐ | 𝚷 | 𝛑 | 𝛱 | 𝜋 | ||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|

Unicode name |
N-ARY PRODUCT | N-ARY COPRODUCT | MATHEMATICAL BOLD CAPITAL PI |
MATHEMATICAL BOLD SMALL PI |
MATHEMATICAL ITALIC CAPITAL PI |
MATHEMATICAL ITALIC SMALL PI | ||||||

Encodings | decimal | hex | decimal | hex | decimal | hex | decimal | hex | decimal | hex | decimal | hex |

Unicode | 8719 | U+220F | 8720 | U+2210 | 120503 | U+1D6B7 | 120529 | U+1D6D1 | 120561 | U+1D6F1 | 120587 | U+1D70B |

UTF-8 | 226 136 143 | E2 88 8F | 226 136 144 | E2 88 90 | 240 157 154 183 | F0 9D 9A B7 | 240 157 155 145 | F0 9D 9B 91 | 240 157 155 177 | F0 9D 9B B1 | 240 157 156 139 | F0 9D 9C 8B |

UTF-16 | 8719 | 220F | 8720 | 2210 | 55349 57015 | D835 DEB7 | 55349 57041 | D835 DED1 | 55349 57073 | D835 DEF1 | 55349 57099 | D835 DF0B |

Numeric character reference | ∏ |
∏ |
∐ |
∐ |
𝚷 |
𝚷 |
𝛑 |
𝛑 |
𝛱 |
𝛱 |
𝜋 |
𝜋 |

Named character reference | ∏, ∏ | ∐, ∐ |

Preview | 𝜫 | 𝝅 | 𝝥 | 𝝿 | 𝞟 | 𝞹 | ||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|

Unicode name |
MATHEMATICAL BOLD ITALIC CAPITAL PI |
MATHEMATICAL BOLD ITALIC SMALL PI |
MATHEMATICAL SANS-SERIF BOLD CAPITAL PI |
MATHEMATICAL SANS-SERIF BOLD SMALL PI |
MATHEMATICAL SANS-SERIF BOLD ITALIC CAPITAL PI |
MATHEMATICAL SANS-SERIF BOLD ITALIC SMALL PI | ||||||

Encodings | decimal | hex | decimal | hex | decimal | hex | decimal | hex | decimal | hex | decimal | hex |

Unicode | 120619 | U+1D72B | 120645 | U+1D745 | 120677 | U+1D765 | 120703 | U+1D77F | 120735 | U+1D79F | 120761 | U+1D7B9 |

UTF-8 | 240 157 156 171 | F0 9D 9C AB | 240 157 157 133 | F0 9D 9D 85 | 240 157 157 165 | F0 9D 9D A5 | 240 157 157 191 | F0 9D 9D BF | 240 157 158 159 | F0 9D 9E 9F | 240 157 158 185 | F0 9D 9E B9 |

UTF-16 | 55349 57131 | D835 DF2B | 55349 57157 | D835 DF45 | 55349 57189 | D835 DF65 | 55349 57215 | D835 DF7F | 55349 57247 | D835 DF9F | 55349 57273 | D835 DFB9 |

Numeric character reference | 𝜫 |
𝜫 |
𝝅 |
𝝅 |
𝝥 |
𝝥 |
𝝿 |
𝝿 |
𝞟 |
𝞟 |
𝞹 |
𝞹 |

Preview | ℿ | ℼ | ||
---|---|---|---|---|

Unicode name |
DOUBLE-STRUCK CAPITAL PI | DOUBLE-STRUCK SMALL PI | ||

Encodings | decimal | hex | decimal | hex |

Unicode | 8511 | U+213F | 8508 | U+213C |

UTF-8 | 226 132 191 | E2 84 BF | 226 132 188 | E2 84 BC |

Numeric character reference | ℿ |
ℿ |
ℼ |
ℼ |

The character encodings in the tables above are intended for use as mathematical symbols. Text written in the Greek language (i.e. words, as opposed to mathematics) should not come from any of the tables on this page, but instead should use the normal Greek letters, which have different code numbers and often a different appearance. Using the mathematical symbols to display words (or vice versa) is likely to result in inconsistent spacing and a clumsy, mismatched appearance.

- ?, ? - Pe (Cyrillic)
- P, p - Pe (Latin)
- Greek letters used in mathematics, science, and engineering# (pi)
- Tau

**^**"Jim Evans' Polyamory Pride Flag". Archived from the original on November 10, 2014.**^**"Pomega".*Eric Weisstein's World of Physics*. wolfram.com.**^**Outline for Weeks 14&15, Astronomy 225 Spring 2008 Archived 2010-06-15 at the Wayback Machine**^**"Unicode characters supported by the Calibri font".*fileformat.info*.**^**Unicode Code Charts: Greek and Coptic (Range: 0370-03FF)

This article uses material from the Wikipedia page available here. It is released under the Creative Commons Attribution-Share-Alike License 3.0.

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