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sigma notation

The compact \sum symbol for writing a sum of many similar terms without writing every one out.

Sigma notation \displaystyle\sum_{i=1}^{n} a_i means a_1 + a_2 + \cdots + a_n — the index i runs from the lower to the upper bound, and each term is added into the running total.

Examples

  • \displaystyle\sum_{i=1}^{4} i^2 = 1+4+9+16 = 30.

See also

Riemann sum
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