greek_letters.txt (558B)
1 =============================================================================== 2 Greek Letters (Meaning) 3 =============================================================================== 4 5 ∑ is the summation sign — capital sigma, Greek for "S", standing for "sum". It's shorthand for "add up a bunch of terms." 6 7 n 8 ∑ aᵢ= a¹+a²+a³+...+aₙ 9 i=1 10 11 i is the index variable (a counter, like a loop variable) 12 i = 1 below the sigma is where the counter starts 13 n above is where it ends (inclusive) 14 a_i is the term — the thing you evaluate at each value of i