When we want to sum up some numbers in math, we don't just explicitly write down in plain text "sum up all the following, where i starts as 2 and then is continuesly incremented all the way up to and with 5". Instead we use the sigma symbol to indicate just that.
Like the case of the sigma symbol, how would I mathematically express that a certain process, or calculation, should be repeated x amount of times?
Example: (context: neural network)
You will in a feedforward neural network have to calculate the output and then update all of the weights a lot of times (easily exceeds 1000 iterations). Now instead of writing this out in words, is there a mathematical way of expressing this as there were with the case of the sigma symbol?