U+2218\circ∘∘<mo>∘</mo>Semantic identity and intent
Characters to distinguish
- ↦ — Maps To
Use ∘ in the right format
Meaning and usage
Combines two functions so that the output of one becomes the input of the other.
Write (f ∘ g)(x) when g is applied first and f is applied to the result.
Pronunciation: function composition
Formula examples
(f∘g)(x)=f(g(x))How to type Function Composition
- Windows
- Use Character Map or enter U+2218 in a Unicode-aware application.
- macOS
- Open Character Viewer with Control–Command–Space and search by the symbol name.
- Microsoft Word
- In an equation, type \circ and press Space when Word supports the command.
- iPhone and iPad
- Copy and paste ∘, or use a math/LaTeX app. The standard iOS keyboard may not expose every mathematical symbol.
- Android
- Copy and paste ∘, or use a math keyboard or LaTeX editor. Keyboard layouts vary by device and app.
- Google Docs
- For plain text, paste ∘ or use Insert → Special characters. For structured math, use the equation editor and verify \circ.
- Excel
- Paste ∘ into a cell or use Insert → Symbol when available. Ordinary cells preserve the character but do not interpret LaTeX commands.
Common mistakes
- Check whether ∘ is acting as an operator, differential, index, or variable in the surrounding expression; Write (f ∘ g)(x) when g is applied first and f is applied to the result.
- For plain text, copy ∘ as U+2218; for structured equations, use \circ in math mode. A look-alike glyph or image can break search, accessibility, or parsing when the intended character is Function Composition.
When to use ∘
- Use ∘ in plain text when a Unicode character is appropriate and the destination preserves U+2218.
- Use \circ in an equation editor when mathematical spacing or structure matters.
- Define the local meaning when Function Composition is used in functions operators, algebra, differential equations with a field-specific convention.
Look-alikes and related characters
- ↦ — Maps To
Font and compatibility notes
Glyph shape can vary by font. Verify the code point after copying, and prefer LaTeX or MathML for structured equations.
Continue the workflow
From Function Composition to a finished equation
- Copy the characterUse ∘ in plain text when Unicode is accepted.
- Choose a structured formatUse
\circfor LaTeX or the MathML snippet for accessible web equations. - Edit or convertOpen the value in the editor or converter without retyping it.
Review and source notes
Quality tier: specialist
Last reviewed: 2026-07-23
Review method: Catalog review of character identity and notation mappings.
Verified against: Unicode Standard, Unicode mathematical notation guidance, and established LaTeX/MathML syntax.
Reference sources
- The Unicode StandardUnicode Consortium — Character identity, encoding, names, and conformance.
- Unicode Character Code ChartsUnicode Consortium — Code points and official character charts.
Frequently asked questions
What does the Function Composition symbol mean?
Combines two functions so that the output of one becomes the input of the other.
What is the LaTeX command for ∘?
Use \circ in a compatible math environment.
Can I copy ∘ as Unicode?
Yes. Use the copy button above to copy the Unicode character directly.