Deriving Average Without Totals

Even an old dog like me learns something new every day. Let’s say you need a program that receives a sequence of numbers and output the current average. How do you do this efficiently? The naive solution is to to keep track of two variables: total # add up all numbers seen so far count # a count of how many numbers seen so far This way, at any step, you can calculate the current average using total/count.

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Vocabulary

bind Sometimes a synonym for “map” conflate combine disjoint separate, e.g., odd numbers and even numbers are disjoint disjunction inclusive or – if one of the inputs is True extrinsic not intrinsic federated Top-down delegation of responsibilities; Has a single point of failure at the top. PID controller control loop feedback mechanism e.g., curise control 99%ile Abbreviation of percentile EBNF Extended Backus-Naur Form Useful for defining the syntax of a programming language EBNF terminal a token/word/chunk in EBNF Alpha Αα Beta Ββ Gamma Γγ Delta Δδ Commonly denotes ‘difference’ Epsilon Εε Used in Greedy-Epsilon algo for multi-armed bandit problems Error margin in floating point comparisons.