Trace:

nan

This shows you the differences between two versions of the page.

Both sides previous revision Previous revision | |||

nan [Sun Oct 31 19:06:53 2010] Gray |
nan [Fri Feb 25 17:31:29 2011] Alexander |
||
---|---|---|---|

Line 2: | Line 2: | ||

In computing, NaN, which stands for Not a Number, is a value or symbol that is usually produced as a result of an operation on invalid input operands. For example, most floating-point units are unable to explicitly calculate the square root of negative numbers, and will instead indicate that the operation was invalid and return a NaN result. | In computing, NaN, which stands for Not a Number, is a value or symbol that is usually produced as a result of an operation on invalid input operands. For example, most floating-point units are unable to explicitly calculate the square root of negative numbers, and will instead indicate that the operation was invalid and return a NaN result. | ||

- | An invalid operation is not the same as an arithmetic overflow (which returns a positive or negative infinity). Arithmetic operations involving NaN always produce NaN, allowing the value to propagate through a calculation so that errors can be detected at the end without extensive testing during intermediate stages. | + | An invalid operation is not the same as an arithmetic overflow (which returns a positive or negative infinity). Arithmetic operations involving NaN always produce NaN, allowing the value to propagate through a calculation so that errors can be detected at the end without extensive testing during intermediate stages. A NaN does not compare equal to any number or NaN. |

- | | + | |

- | A NaN does not compare equal to any number or NaN. You can therefore test whether a variable has a NaN value by comparing it to itself: if ''x == x'' returns false (0), then x is a NaN code. | + | |

==== How does a NaN appear? ==== | ==== How does a NaN appear? ==== |

nan.txt · Last modified: Sun Nov 8 12:21:24 2015 (external edit)

Except where otherwise noted, content on this wiki is licensed under the following license: CC Attribution-Share Alike 4.0 International