| slovo | definícia |
si prefix
(foldoc) | SI prefix
The standard metric prefixes used in the
Système International d'Unités (SI) conventions for
scientific measurement.
Here are the SI magnifying prefixes, along with the
corresponding binary interpretations in common use:
prefix abr decimal binary
yocto- 1000^-8
zepto- 1000^-7
atto- 1000^-6
femto- f 1000^-5
pico- p 1000^-4
nano- n 1000^-3
micro- * 1000^-2 * Abbreviation: Greek mu
milli- m 1000^-1
kilo- k 1000^1 1024^1 = 2^10 = 1,024
mega- M 1000^2 1024^2 = 2^20 = 1,048,576
giga- G 1000^3 1024^3 = 2^30 = 1,073,741,824
tera- T 1000^4 1024^4 = 2^40 = 1,099,511,627,776
peta- 1000^5 1024^5 = 2^50 = 1,125,899,906,842,624
exa- 1000^6 1024^6 = 2^60 = 1,152,921,504,606,846,976
zetta- 1000^7 1024^7 = 2^70 = 1,180,591,620,717,411,303,424
yotta- 1000^8 1024^8 = 2^80 = 1,208,925,819,614,629,174,706,176
"Femto" and "atto" derive not from Greek but from Danish.
The abbreviated forms of these prefixes are common in
electronics and physics.
When used with bytes of storage, these prefixes usually denote
multiplication by powers of 1024 = 2^10 (K, M, G and T are
common in computing). Thus "MB" stands for megabytes (2^20
bytes). This common practice goes against the edicts of the
BIPM who deprecate the use of these prefixes for powers of
two. The formal SI prefix for 1000 is lower case "k"; some,
including this dictionary, use this strictly, reserving upper
case "K" for multiplication by 1024 (KB is thus "kilobytes").
Also, in data transfer rates the prefixes stand for powers of
ten so, for example, 28.8 kb/s means 28,800 bits per second.
The unit is often dropped so one may talk of "a 40K salary"
(40000 dollars) or "2 meg of disk space" (2*2^20 bytes).
The accepted pronunciation of the initial G of "giga-" is
hard, /gi'ga/.
Confusing 1000 and 1024 (or other powers of 2 and 10 close in
magnitude) - for example, describing a memory in units of 500K
or 524K instead of 512K - is a sure sign of the marketroid.
For example, 3.5" microfloppies are often described as
storing "1.44 MB". In fact, this is completely specious. The
correct size is 1440 KB = 1440 * 1024 = 1474560 bytes. Alas,
this point is probably lost on the world forever.
In 1993, hacker Morgan Burke proposed, to general approval on
Usenet, the following additional prefixes: groucho (10^-30),
harpo (10^-27), harpi (10^27), grouchi (10^30). This would
leave the prefixes zeppo-, gummo-, and chico- available for
future expansion. Sadly, there is little immediate prospect
that Mr. Burke's eminently sensible proposal will be ratified.
(2009-09-01)
|
| | podobné slovo | definícia |
si prefix
(foldoc) | SI prefix
The standard metric prefixes used in the
Système International d'Unités (SI) conventions for
scientific measurement.
Here are the SI magnifying prefixes, along with the
corresponding binary interpretations in common use:
prefix abr decimal binary
yocto- 1000^-8
zepto- 1000^-7
atto- 1000^-6
femto- f 1000^-5
pico- p 1000^-4
nano- n 1000^-3
micro- * 1000^-2 * Abbreviation: Greek mu
milli- m 1000^-1
kilo- k 1000^1 1024^1 = 2^10 = 1,024
mega- M 1000^2 1024^2 = 2^20 = 1,048,576
giga- G 1000^3 1024^3 = 2^30 = 1,073,741,824
tera- T 1000^4 1024^4 = 2^40 = 1,099,511,627,776
peta- 1000^5 1024^5 = 2^50 = 1,125,899,906,842,624
exa- 1000^6 1024^6 = 2^60 = 1,152,921,504,606,846,976
zetta- 1000^7 1024^7 = 2^70 = 1,180,591,620,717,411,303,424
yotta- 1000^8 1024^8 = 2^80 = 1,208,925,819,614,629,174,706,176
"Femto" and "atto" derive not from Greek but from Danish.
The abbreviated forms of these prefixes are common in
electronics and physics.
When used with bytes of storage, these prefixes usually denote
multiplication by powers of 1024 = 2^10 (K, M, G and T are
common in computing). Thus "MB" stands for megabytes (2^20
bytes). This common practice goes against the edicts of the
BIPM who deprecate the use of these prefixes for powers of
two. The formal SI prefix for 1000 is lower case "k"; some,
including this dictionary, use this strictly, reserving upper
case "K" for multiplication by 1024 (KB is thus "kilobytes").
Also, in data transfer rates the prefixes stand for powers of
ten so, for example, 28.8 kb/s means 28,800 bits per second.
The unit is often dropped so one may talk of "a 40K salary"
(40000 dollars) or "2 meg of disk space" (2*2^20 bytes).
The accepted pronunciation of the initial G of "giga-" is
hard, /gi'ga/.
Confusing 1000 and 1024 (or other powers of 2 and 10 close in
magnitude) - for example, describing a memory in units of 500K
or 524K instead of 512K - is a sure sign of the marketroid.
For example, 3.5" microfloppies are often described as
storing "1.44 MB". In fact, this is completely specious. The
correct size is 1440 KB = 1440 * 1024 = 1474560 bytes. Alas,
this point is probably lost on the world forever.
In 1993, hacker Morgan Burke proposed, to general approval on
Usenet, the following additional prefixes: groucho (10^-30),
harpo (10^-27), harpi (10^27), grouchi (10^30). This would
leave the prefixes zeppo-, gummo-, and chico- available for
future expansion. Sadly, there is little immediate prospect
that Mr. Burke's eminently sensible proposal will be ratified.
(2009-09-01)
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