The logarithm of a number is the exponent by which a fixed number, the base, has to be raised to produce that number. For example, the logarithm of 1000 to base 10 is 3, because 1000 is 10 to the power 3: 1000 = 10³ = 10 × 10 × 10. Logarithms were introduced by John Napier in the early 17th century as a means to simplify calculations. They were rapidly adopted by scientists and engineers to perform computations using slide rules and logarithm tables. These devices rely on the fact—important in its own right—that the logarithm of a product is the sum of the logarithms of the factors. Logarithmic scales reduce wide-ranging quantities to smaller scopes. For example, the decibel is a logarithmic unit quantifying sound pressure and voltage ratios. Logarithms describe musical intervals, measure the complexity of algorithms, and appear in formulas counting prime numbers. They also inform some models in psychophysics and can aid in forensic accounting.

Read the rest of this article: http://en.wikipedia.org/wiki/Logarithm

_______________________________ Today's selected anniversaries:

1257:

Kraków in Poland received city rights based on the Magdeburg law. http://en.wikipedia.org/wiki/Krak%C3%B3w

1305:

Raymond Bertrand de Got became Pope Clement V, succeeding Pope Benedict XI who died one year earlier. http://en.wikipedia.org/wiki/Pope_Clement_V

1956:

American singer Elvis Presley performed "Hound Dog" to a nationwide television audience on the The Milton Berle Show, an appearance that generated many letters of protest. http://en.wikipedia.org/wiki/Hound_Dog_%28song%29

1967:

The Six-Day War began with an Israeli Air Force preemptive strike that destroyed about 450 total aircraft of the Egyptian, Jordanian and Syrian Air Forces on the ground. http://en.wikipedia.org/wiki/Six-Day_War

1989:

An anonymous demonstrator, later dubbed "Tank Man", single-handedly stopped a column of Chinese tanks during the Tiananmen Square protests before being dragged aside. http://en.wikipedia.org/wiki/Tank_Man

_____________________________ Wiktionary's word of the day:

funest (adj): Causing death or disaster; fatal, catastrophic http://en.wiktionary.org/wiki/funest

___________________________ Wikiquote quote of the day:

The ideas of economists and political philosophers, both when they are right and when they are wrong, are more powerful than is commonly understood. Indeed the world is ruled by little else. Practical men, who believe themselves to be quite exempt from any intellectual influence, are usually the slaves of some defunct economist. Madmen in authority, who hear voices in the air, are distilling their frenzy from some academic scribbler of a few years back. --John Maynard Keynes http://en.wikiquote.org/wiki/John_Maynard_Keynes