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not a number
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(Definition)
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In a computer, not a number (usually abbreviated NaN) indicates that an arithmetical operation has resulted in a value that is not a number understood (or representable) by the computer. Division by zero is one frequent cause of a result being NaN. Asking for the square root of a negative number is another
operation that can result in NaN (unless the computer has been programmed to recognize imaginary numbers).
NaN is not a specific value that can be tested for with the usual comparison operators. The programmer is advised to test for NaN with a special function provided by the programming language (such as isNaN(x) in JavaScript.
Generally, computer algebra systems do not report NaN results even if they do display an error message for a given operation.
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- David Flanagan, JavaScript the Definitive Guide: The Definitive Guide. New York: O'Reilly (2006): 24
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"not a number" is owned by PrimeFan.
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Cross-references: even, computer algebra systems, JavaScript, language, function, operators, imaginary numbers, negative number, square root, division by zero, representable, operation, arithmetical, computer
There are 2 references to this entry.
This is version 1 of not a number, born on 2008-07-18.
Object id is 10824, canonical name is NotANumber.
Accessed 641 times total.
Classification:
| AMS MSC: | 68P01 (Computer science :: Theory of data :: General) |
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Pending Errata and Addenda
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