Giga-
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- For the Baroque dance, see gigue. For the television station, see GIGA Television.
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Giga- (symbol: G) is a prefix in the SI system of units denoting 109, or 1,000,000,000 (1 thousand million). The Oxford English Dictionary reports the earliest written use of giga- in this sense to be in the Reports of the IUPAC 14th Conference in 1947: "The following prefixes to abbreviations for the names of units should be used: G giga- 109×". Giga- comes from the Greek γίγας, meaning giant.
When referring to computing information units, such as gigabit or gigabyte, giga- can sometimes mean 1,073,741,824 (230), (Though such use is incorrect) and is better used only to denote strictly 1,000,000,000 (109). Any ambiguity is best resolved from context. The binary prefix gibi- has been standardized for 230, while reserving giga- exclusively for 109, to resolve this ambiguity, but has yet to achieve widespread usage. See binary prefix.
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[edit] Pronunciation
In English the initial g of giga is properly pronounced with a hard g (as in giggle) but is sometimes pronounced with a soft g (as in giant). According to the American writer Self, in the 1920s a German committee member of the International Electrotechnical Commission proposed giga- as a prefix for 109, drawing on a verse by the humorous poet Christian Morgenstern that appeared in the third (1908) edition of Galgenlieder (Gallows Songs). This suggests a hard German g was originally intended as the pronunciation. Self was unable to ascertain at what point the soft g pronunciation came into occasional use, but as of 1995 current practice had returned to hard g.[1] A prominent example of the soft G pronunciation is found in the 1985 movie Back to the Future, where gigawatts was pronounced as jigawatts.
In the United States, it is well documented that the National Bureau of Standards issued pronunciation guides for the metric prefixes in the 1960s and again as late as the 1980s, giving the 'g' in "giga" a soft "j" sound, thus formalizing the pronunciation as "jiga"[2].
[edit] Common usage
- gigabyte — for instance, in hard disk capacity, 120 GB = 120,000,000,000 bytes; in file sizes, 1 GB = 1,073,741,824 bytes (also termed a gibibyte to reduce ambiguity)
- gigahertz — clock rate of a CPU, for instance, 3 GHz = 3,000,000,000 Hz
- gigabit — bandwidth of a network, for instance, 1 Gbit/s = 1,000,000,000 bit/s
- gigayear or gigaannum — one billion (<math>10^9</math>) complete Julian rotation periods of the Earth about the Sun. (sometimes abbr. Gyr, but the preferred usage is Ga)
| 1000n | 10n | Prefix | Symbol | Since[1] | Short scale | Long scale | Decimal equivalent in SI writing style |
|---|---|---|---|---|---|---|---|
| 10008 | 1024 | yotta- | Y | 1991 | Septillion | Quadrillion | 1 000 000 000 000 000 000 000 000 |
| 10007 | 1021 | zetta- | Z | 1991 | Sextillion | Trilliard (thousand trillion) | 1 000 000 000 000 000 000 000 |
| 10006 | 1018 | exa- | E | 1975 | Quintillion | Trillion | 1 000 000 000 000 000 000 |
| 10005 | 1015 | peta- | P | 1975 | Quadrillion | Billiard (thousand billion) | 1 000 000 000 000 000 |
| 10004 | 1012 | tera- | T | 1960 | Trillion | Billion | 1 000 000 000 000 |
| 10003 | 109 | giga- | G | 1960 | Billion | Milliard (thousand million) | 1 000 000 000 |
| 10002 | 106 | mega- | M | 1960 | Million | 1 000 000 | |
| 10001 | 103 | kilo- | k | 1795 | Thousand | 1 000 | |
| 10002/3 | 102 | hecto- | h | 1795 | Hundred | 100 | |
| 10001/3 | 101 | deca- | da | 1795 | Ten | 10 | |
| 10000 | 100 | (none) | (none) | NA | One | 1 | |
| 1000−1/3 | 10−1 | deci- | d | 1795 | Tenth | 0.1 | |
| 1000−2/3 | 10−2 | centi- | c | 1795 | Hundredth | 0.01 | |
| 1000−1 | 10−3 | milli- | m | 1795 | Thousandth | 0.001 | |
| 1000−2 | 10−6 | micro- | µ | 1960[2] | Millionth | 0.000 001 | |
| 1000−3 | 10−9 | nano- | n | 1960 | Billionth | Milliardth | 0.000 000 001 |
| 1000−4 | 10−12 | pico- | p | 1960 | Trillionth | Billionth | 0.000 000 000 001 |
| 1000−5 | 10−15 | femto- | f | 1964 | Quadrillionth | Billiardth | 0.000 000 000 000 001 |
| 1000−6 | 10−18 | atto- | a | 1964 | Quintillionth | Trillionth | 0.000 000 000 000 000 001 |
| 1000−7 | 10−21 | zepto- | z | 1991 | Sextillionth | Trilliardth | 0.000 000 000 000 000 000 001 |
| 1000−8 | 10−24 | yocto- | y | 1991 | Septillionth | Quadrillionth | 0.000 000 000 000 000 000 000 001 |
| Notes: 1. The 1795 dates identify prefixes in use since the metric system was introduced. The other dates are not necessarily dates of first use, but rather the date of recognition by a resolution of the CGPM, which first met in 1889. 2. The micron was earlier recognized by the CGPM in 1948; that decision was abrogated in 1967-68. | |||||||
[edit] See also
[edit] Notes and references
[edit] External links
- BIPM websitebr:Giga
ca:Giga cs:Giga et:Giga- es:Giga fa:گیگا fr:Giga ko:기가 it:Giga he:תחיליות במערכת היחידות הבינלאומית#.D7.92.D7.99.D7.92.D7.94 mk:Гига (единица) nl:Giga ja:ギガ no:Giga nn:Giga nds:Giga pl:Giga pt:Giga sk:Giga sl:Giga sr:Гига fi:Giga sv:Giga vi:Giga
