👉 Sigmat, also known as sigma or sigma notation, is a mathematical notation used to express summation of values. It is often seen in programming and data analysis where we need to sum up multiple values together. For example, if we have an array `a` containing 5 elements [1,2,3,4,5], the following code would sum up all these elements: ```python sum = 0 for i in range(len(a)): sum += a[i]
