\Sigma - LaTeX Symbol

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Σ

\Sigma

The Greek letter Sigma (\Sigma) is used in mathematics to denote summation, which is the addition of a sequence of numbers. It is also used in statistics to represent the sum of a set of values or to denote the standard deviation when used in lowercase (\sigma).

Examples

Σ_{i = 1}^{n} i = \frac{n ( n + 1 )}{2}

Summation of the first n natural numbers.

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

Σ_{k = 1}^{m} a_{k} = a_{1} + a_{2} + \dots + a_{m}

General representation of the sum of a sequence.

\Sigma_{k=1}^{m} a_k = a_1 + a_2 + \cdots + a_m

Σ_{i = 1}^{n} (x_{i} - \overset{x}{ˉ})^{2}

Summation used in the calculation of variance.

\Sigma_{i=1}^{n} (x_i - \bar{x})^2