X̂ is the

Latin letter The Latin script, also known as the Roman script, is a writing system based on the letters of the classical Latin alphabet, derived from a form of the Greek alphabet which was in use in the ancient Greek city of Cumae in Magna Graecia. The Gree ...

''X'' with a

circumflex The circumflex () is a diacritic in the Latin and Greek scripts that is also used in the written forms of many languages and in various romanization and transcription schemes. It received its English name from "bent around"a translation of ...

. The letter is used in the modern

orthography An orthography is a set of convention (norm), conventions for writing a language, including norms of spelling, punctuation, Word#Word boundaries, word boundaries, capitalization, hyphenation, and Emphasis (typography), emphasis. Most national ...

of the

Aleut language Aleut ( ) or is the language spoken by the Aleut living in the Aleutian Islands, Pribilof Islands, Commander Islands, and the Alaska Peninsula (in Aleut , the origin of the state name Alaska). Aleut is the sole language in the Aleut branch of ...

and in the current

Alaska Native Language Center The Alaska Native Language Center, established in 1972 in Fairbanks, Alaska, is a research center focusing on the research and documentation of the Native languages of Alaska. It publishes grammars, dictionaries, folklore collections and research m ...

alphabet of the

Haida language Haida (', ', ', ') is the language of the Haida people, spoken in the Haida Gwaii archipelago off the coast of western Canada and on Prince of Wales Island in Alaska. An endangered language, Haida currently has 24 native speakers, though revit ...

. In both cases, it represents the sound . In mathematics, x̂ often refers to the

unit vector In mathematics, a unit vector in a normed vector space is a Vector (mathematics and physics), vector (often a vector (geometry), spatial vector) of Norm (mathematics), length 1. A unit vector is often denoted by a lowercase letter with a circumfle ...

in the +X direction. In statistics, it can also represent the predicted value for x, consistent with the

hat notation A "hat" (circumflex (ˆ)), placed over a symbol is a mathematical notation with various uses. Estimated value In statistics, a circumflex (ˆ), called a "hat", is used to denote an estimator or an estimated value. For example, in the context of ...

References

Aleut language Haida language {{Latin-script-stub