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 = 10<sup>3</sup> = 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>
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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>
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Wiktionary's word of the day:
funest (adj):
Causing death or disaster; fatal, catastrophic
<http://en.wiktionary.org/wiki/funest>
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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>