# \sigma

The σ symbol (Greek small letter sigma, U+03C3), written as \sigma in LaTeX math mode.

https://texform.dev/latex/symbols/sigma

## Metadata

| Field | Value |
| --- | --- |
| Topic | [Greek letters](https://texform.dev/latex/topics/greek) |
| Packages | base |
| Allowed mode | math |
| Glyph | σ |
| Unicode | U+03C3 GREEK SMALL LETTER SIGMA |
| Delimiter | No |

## Syntax

```latex
\sigma
```

Takes no arguments.

## Common tasks

### How to write a small sigma

```latex
\sigma
```

[Open in Playground](https://play.texform.dev/?input=%5Csigma)

### How to write a standard deviation

```latex
X\sim\mathcal{N}(\mu,\sigma^2)
```

[Open in Playground](https://play.texform.dev/?input=X%5Csim%5Cmathcal%7BN%7D%28%5Cmu%2C%5Csigma%5E2%29)

### How to write a Pauli matrix

The summation operator is \sum, not \sigma.

```latex
\sigma_x,\sigma_y,\sigma_z
```

[Open in Playground](https://play.texform.dev/?input=%5Csigma_x%2C%5Csigma_y%2C%5Csigma_z)

## Usage frequency

6.99% of formulas in the measured corpus contain this entry, rank 11 of 474 entries with frequency data.

## In TeXForm

TeXForm parses this entry as a character leaf mapped to U+03C3 (GREEK SMALL LETTER SIGMA).