An angle bracket is the combination of a bra and ket (bra+ket = bracket) which represents the inner product
of two functions or vectors (or 1-forms),
in a function space, or
in a vector space. Here, 
represents the adjoint.
The expression 
is also commonly used to denote the expectation
value of a variable 
.
See also
Bra,
Brace,
Bracket,
Differential
k-Form,
Expectation Value,
Ket,
One-Form,
Parenthesis,
Square Bracket
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References
Bringhurst, R. The Elements of Typographic Style, 2nd ed. Point Roberts, WA: Hartley and Marks,
p. 271, 1997.Referenced on Wolfram|Alpha
Angle Bracket
Cite this as:
Weisstein, Eric W. "Angle Bracket." From
MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/AngleBracket.html
Subject classifications
