In mathematics, an operator is a function, usually of a special kind depending on the topic. For instance, in linear algebra an "operator" is a linear operator. In analysis an "operator" may be a differential operator, generalizing the ordinary derivative, or an integral operator, generalizing ordinary integration. Often, an "operator" is a function that acts on functions to produce other functions; or it may be a generalization of such a function, as in linear algebra, where some of the terminology reflects the origin of the subject in operations on the functions that are solutions of differential equations. One often thinks of an operator as dynamic, changing something into something else, whence the name; but this is only a way of thinking and not a formal definition.

An operator name or operator symbol is a notation that denotes a particular operator. When there is no danger of confusion, an operator name or operator symbol may be referred to more briefly as an "operator". Strictly speaking, however, the operator is a mathematical object and not the syntactic entity that denotes it. The reason for identifying it with its notation is that there are some operators that have come to have standard notations.

An example of an operator, specifically a differential operator, is the derivative itself. The corresponding operator name D, when placed before a differentiable function f, indicates that the function is to be differentiated with respect to the variable.

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Christian Science Monitor | World

Syria eyes an edge amid Russia-U.S. rift
Thu, 28 Aug 2008 01:00:00 -0500
Damascus is seeking an arms deal with Moscow, a move that would bolster its position in the Middle East.
Sri Lanka advances on rebel base
Thu, 28 Aug 2008 01:00:00 -0500
While the military is making gains on the Tamil Tigers, it could become mired in guerrilla attacks.
Russia's case on Georgia territories: Like Kosovo or not?
Thu, 28 Aug 2008 01:00:00 -0500
Tuesday, after invoking Kosovo to recognize two separatist republics, Russia changed its tack.

NPR Topics: World

Civilian Casualties Mount In Afghanistan
Wed, 27 Aug 2008 15:41:00 -0400
After a joint U.S.-Afghan bombing raid killed 90 Afghan civilians, Afghan support for U.S. military action is waning. Officials say bad intelligence probably led to the deadly strike aimed at Taliban fighters.
Dems to Highlight Biden, Obama on Foreign Policy
Wed, 27 Aug 2008 15:39:00 -0400
Wednesday's speeches are designed to show how Biden and Obama will mesh in their approach to America's role in the world. But some question about how closely the ideas of Biden and Obama align.
U.N.: U.S.-Led Strike Killed Dozens Of Afghan Children
Wed, 27 Aug 2008 13:00:00 -0400
The Afghan government is demanding that the U.S. and NATO presence there come under greater scrutiny. The move comes after the U.N. determined a U.S.-led air strike last week killed 90 civilians, most of them children.

NYT > World

Russia Sees New Realm of Concern: Black Sea
Wed, 27 Aug 2008 19:08:59 -0000
Russian commanders said they were growing alarmed at the number of NATO warships sailing into the Black Sea.
U.S. to Hand Over Security in Anbar to the Iraqis
Wed, 27 Aug 2008 21:01:46 -0000
The U.S. military will hand over responsibility for the security of Anbar Province, one of the most violent regions in Iraq, as early as next Monday, officials said.
Taliban Gain New Foothold in Afghan City
Wed, 27 Aug 2008 15:52:01 -0000
A June jailbreak highlighted the Afghan government’s frailty, and the security situation has worsened since.

World business news - CNNMoney.com

How one bank avoided the meltdown
Wed, 27 Aug 2008 13:17:10 -0400
Not every player in banking is getting clobbered these days. BNP Paribas, which sparked part of the very first global credit-crunch panic when it froze three funds on Aug. 9, 2007, may emerge as the bank least affected by the industry's carnage.
Japan's Ricoh to buy IKON for $1.6B
Wed, 27 Aug 2008 13:14:33 -0400
Read full story for latest details.
Toyota raises hybrid prices in Japan
Mon, 25 Aug 2008 10:57:05 -0400
Automaker increases prices for the Prius and Harrier hybrids in response to the soaring cost of raw materials.

FRONTLINE/World - Reports | PBS

China: Kung Fu English
Mon, 18 Aug 2008 21:00:00 -0500
Xinjiang province in remote western China is best known for the Taklamakan desert and the struggle for autonomy among the region's Muslim Uighur people. It's also considered a provincial backwater looked down upon by the Western influenced provinces in the east. Xinjiang native Jake Yong set out to change that perception by teaching himself -- and others -- to speak English.
The Arrest of Radovan Karadzic
Wed, 23 Jul 2008 21:00:00 -0500
Hasan Nuhanovic lost his father and brother at Srebrenica. FRONTLINE/World spoke to him from Sarajevo about the capture this week of the man who ordered the massacre.
Burma: After the Storm
Tue, 22 Jul 2008 21:00:00 -0500
Capturing recent, dramatic footage inside Burma, our correspondent shares his video diary and talks about the mood among dissidents there.

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