# Defining binary operators inner product angle brackets

**URL:** <https://discourse.julialang.org/t/defining-binary-operators-inner-product-angle-brackets/48025>\
**Category:** Specific Domains\
**Tags:** question\
**Created:** [October 9, 2020, 10:36am UTC](https://discourse.julialang.org/t/defining-binary-operators-inner-product-angle-brackets/48025 "2020-10-09T10:36:52Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![kapple](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kapple/32/218915_2.png) [@kapple](https://discourse.julialang.org/u/kapple)\
**Post date:** [October 9, 2020, 10:36am UTC](https://discourse.julialang.org/t/defining-binary-operators-inner-product-angle-brackets/48025/1 "2020-10-09T10:36:53Z")

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I’d like to define an inner product, and I’m wondering if it’s possible to call it using the angle brackets.

```julia
using QuadGK

# "Definition" (quote-unquote)
⟨u, v⟩ = quadgk(x -> u(x)*v(x), 0, 1, rtol = 1e-3)

# Usage
u(x) = x^2
v(x) = x^3
M = ⟨u, v⟩

```

I’ve seen that there is [a list of supported symbols](https://docs.julialang.org/en/v1/base/math/#Customizable-binary-operators) but with the [linked file provided](https://github.com/JuliaLang/julia/blob/master/src/julia-parser.scm) it was hard to browse/find the angle brackets.

I haven’t been able to find if anyone has tried/done this before.

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<div class="post-metadata">

**Author:** ![simeonschaub](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/simeonschaub/32/216566_2.png) [@simeonschaub](https://discourse.julialang.org/u/simeonschaub)\
**Post date:** [October 9, 2020, 11:37am UTC](https://discourse.julialang.org/t/defining-binary-operators-inner-product-angle-brackets/48025/2 "2020-10-09T11:37:31Z")

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It’s currently not possible to do this, because angle brackets are not valid syntax. See also [https://github.com/JuliaLang/julia/pull/27712](https://github.com/JuliaLang/julia/pull/27712).