LaTeX Sigma (σ) - 完整指南

The Greek letter sigma (σ/Σ) is used for standard deviation, conductivity, and summation.

Symbol Preview

Sigma

LaTeX Code

Method 1: Using \sigma

No package required

Recommended

\sigma

Lowercase sigma

Method 2: Using \Sigma

No package required

Recommended

\Sigma

Uppercase sigma (summation)

Method 3: Using \varsigma

Requires: \usepackage{cmd.package}

\varsigma

Alternative lowercase sigma (final sigma)

LaTeX Sigma 是什么？

Sigma is the eighteenth letter of the Greek alphabet. Lowercase σ represents standard deviation in statistics and conductivity in physics. Uppercase Σ is the summation symbol used to denote the sum of a series. Both forms are fundamental in mathematics and science.

如何在 LaTeX 中使用 Sigma

方法 1：使用 \sigma

✅无需额外包

Lowercase sigma

示例：使用 \sigma

latex

\documentclass{article}

\begin{document}

% Using the Sigma
Text with \sigma

\end{document}

方法 2：使用 \Sigma

✅无需额外包

Uppercase sigma (summation)

示例：使用 \Sigma

latex

\documentclass{article}

\begin{document}

% Using the Sigma
Text with \Sigma

\end{document}

方法 3：使用 \varsigma

⚠️所需包：

\usepackage{cmd.package}

Alternative lowercase sigma (final sigma)

示例：使用 \varsigma

latex

\documentclass{article}
\usepackage{amssymb}
\begin{document}

% Using the Sigma
Text with \varsigma

\end{document}

常见用途

Sigma 符号通常用于以下情况：

Standard Deviation

Represents standard deviation in statistics.

Code

Standard deviation: $\sigma = \sqrt{\frac{1}{N}\sum_{i=1}^{N}(x_i-\mu)^2}$

Output

Standard deviation: σ = √((1/N)Σ(x_i-μ)²)

Summation

Uppercase sigma for summing series.

Code

Sum: $\Sigma_{i=1}^{n} i = \frac{n(n+1)}{2}$

Output

Sum: Σ(i=1 to n) i = n(n+1)/2

Electrical Conductivity

Used in physics for conductivity.

Code

Conductivity: $\sigma = \frac{1}{\rho}$

Output

Conductivity: σ = 1/ρ

完整示例

Summation Formula

Summation formula using uppercase sigma

latex

\documentclass{article}
\begin{document}

The sum of the first $n$ natural numbers: $\Sigma_{i=1}^{n} i = \frac{n(n+1)}{2}$

\end{document}

Normal Distribution

Standard deviation using sigma

latex

\documentclass{article}
\begin{document}

In a normal distribution, about 95% of values fall within 2 standard deviations: $\mu \pm 2\sigma$

\end{document}