Capitalized sigma is used for:
Mathematical summation symbol
For example:
∑Pi, where i= 1, 2, ..., t,
Is to find the sum of P 1+P2+ and ...+angle.
Lowercase σ is used for: statistical standard deviation.
Both the с of Cyrillic alphabet and the S of Latin alphabet are derived from Sigma.
The code name of Sigma, the villain in the series Rockman X, also refers to peace.
This writing means ∑ j =1+2+3+...+n.