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added Xynk units of length
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===[http://www.gnu.org/software/units/ fixed size tables of C structs]===+
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SI Base Units of the 7 Base Quantities:
SI Base Units of the 7 Base Quantities:
<tab class="wikitable" border = "1" cellspacing="3" cellpadding = "3" head = top>
<tab class="wikitable" border = "1" cellspacing="3" cellpadding = "3" head = top>
−Base quantity Name Symbol
+Base Quantity Name Symbol
length meter m
length meter m
mass kilogram kg
mass kilogram kg
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</tab>
</tab>
−Note an anomaly: the basic unit of mass (kg) has a prefix, so have to tolerate g as basic unit also.
+''Note an anomaly: the basic unit of mass (kg) has a prefix, so have to tolerate g as basic unit also.''
Other quantities, called derived quantities, are defined in terms of the seven base quantities via a system of quantity equations.
Other quantities, called derived quantities, are defined in terms of the seven base quantities via a system of quantity equations.
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−===[http://www-ksl.stanford.edu/knowledge-sharing/ontologies/html/physical-quantities/physical-quantities.lisp.html Lisp Ontology of Physical Quantities]===
+===[http://www-ksl.stanford.edu/knowledge-sharing/ontologies/html/physical-quantities/index.html Lisp Ontology of Physical Quantities]===
+Greg R. Olsen and Thomas R. Gruber [http://www-ksl.stanford.edu/knowledge-sharing/papers/engmath.html An Ontology for Engineering Mathematics] In Jon Doyle, Piero Torasso, & Erik Sandewall, Eds., Fourth International Conference on Principles of Knowledge Representation and Reasoning, Gustav Stresemann Institut, Bonn, Germany, Morgan Kaufmann, 1994.
−"The physical-quantities theory defines the basic vocabulary for describing physical quantities in a general form, making explicit the relationships between magnitudes of various orders, units of measure and physical dimensions. It defines the general class physical-quantity and a set of algebraic operators that are total over all physical quantities. Specializations of the physical-quantity class and the operators are defined in other theories (which use this theory).
−Adrian Mariano: dimensional analysis of unit strings using fixed size tables of C structs.
+The theory also describes specific language for physical units such as meters, inches, and pounds, and physical dimensions such as length, time, and mass. The theory provides representational vocabulary to compose units and dimensions from basis sets and to describe the basic relationships between units and physical dimensions. This theory helps support the consistent use of units in expressions relating physical quantities, and it also supports conversion of units needed in calculations."
+===[http://www.gnu.org/software/units/ GNU Units]===
+"GNU Units converts quantities expressed in various systems of measurement to their equivalents in other systems of measurement. Like many similar programs, it can handle multiplicative scale changes. It can also handle nonlinear conversions such as Fahrenheit to Celsius or wire gauge, and it can convert from and to sums of units, such as converting between meters and feet plus inches.
+Beyond simple unit conversions, GNU Units can be used as a general-purpose scientific calculator that keeps track of units in its calculations. You can form arbitrary complex mathematical expressions of dimensions including sums, products, quotients, powers, and even roots of dimensions. Thus you can ensure accuracy and dimensional consistency when working with long expressions that involve many different units that may combine in complex ways."
+Noted in TCL library (see below): "The ideas behind implementation of this package [TCL] is based in part on code written in 1993 by Adrian Mariano which performed dimensional analysis of unit strings using fixed size tables of C structs. After going missing in the late 1990's, Adrian's code has reappeared in the GNU Units program at http://www.gnu.org/software/units/"
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New units and new unit abbreviations can be defined in terms of existing units and abbreviations. It is also possible to define a new primitive unit, although that will probably be unnecessary. New units will most commonly be defined to accommodate non-SI measurement systems, such as defining the unit inch as 2.54 cm."
New units and new unit abbreviations can be defined in terms of existing units and abbreviations. It is also possible to define a new primitive unit, although that will probably be unnecessary. New units will most commonly be defined to accommodate non-SI measurement systems, such as defining the unit inch as 2.54 cm."
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+"The ideas behind implementation of this package [TCL] is based in part on code written in 1993 by Adrian Mariano which performed dimensional analysis of unit strings using fixed size tables of C structs. After going missing in the late 1990's, Adrian's code has reappeared in the GNU Units program at http://www.gnu.org/software/units/"
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+==Units of Length==
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+<tab class="wikitable" border = "1" cellspacing="3" cellpadding = "3" head = top>
+
+Unit Abbr meter point note
+pixel px 3.527778E-04 1 this is actualy device dependent, smallest size element that can be drawn on the screen. We’ll set it to 1 point for the moment
+point pt 3.527778E-04 1 DTP or postscript point
+pica pc 4.233333E-03 12
+line ll 2.116667E-03 6
+thou, mil 0.000025 0.072
+inch [inches] in 0.025400 72
+foot [feet] ft 0.304800 864
+yard yd 0.914400 2592 3 feet, defined in 1959 to be 0.9144 m
+fathom ftm 1.828800 5184
+mile, statute mile mi 1,609.344000 4561920 80 chains
+nautical mile NM, nmi 1852.000000 5.249764E+06 one minute of arc of latitude; 1 knot = 1 nmi/hour
+league 4828.000000 13685760 3 miles
+angstrom Å, A 1.000000E-10 2.834646E-07 Unicode: C5, UTF-8: c3 85, html: Å, option-shift-A; Note: should allow lowercase a or å for unit matching as well
+micrometer,micron µm,um 1.000000E-06 2.834646E-03
+millimeter mm 1.000000E-03 2.834646E+00
+centimeter cm 1.000000E-02 2.834646E+01
+meter m 1 2.834646E+03
+kilometer km 1,000 2.834646E+06
+smoot 1.7018000 4824
+astronomical unit au 1.495979E+11 4E+14
+light year ly 9.460730E+15 3E+19
+parsec pc 3.085678E+16 9E+19
+furlong fur 201.1680000 570,240 10 chains
+peninkulma 10,688.4000000 3.029783E+07 10.6884 km = distance a barking dog can be heard in still air (Finnish)
+poronkusema 7,500.0000000 2.125984E+07 7.5 km = distance a reindeer can travel before needing to stop to urinate
+Lego duplex unit LDU 0.0040000 11.338583 the spacing between the centres of two adjacent Lego studs is defined as exactly 20 LDU; http://webstaff.itn.liu.se/~stegu/lego/LDUlength.pdf
+chain 20.1168000 57,024 22 yards, 4 rods. There are 10 chains in a furlong, and 80 chains in one statute mile. An acre is the area of 10 square chains
+rod, pole, perch 5.0292000 14,256 5.5 feet
+Earth radius R⊕ 6.371000E+06 1.805953E+10
+Hubble length cH0-1 1.305581E+17 3.700859E+20 13.8 billion light years
+lunar distance LD 3.844000E+08 1.089638E+12
+Bohr radius a0 5.291772E-11 1.500030E-07
+natural unit of length λC 3.861593E-13 1.094625E-09
+Planck length lp 1.616199E-35 4.581351E-32 speed of light is 1 Planck length/1 Planck time
+football field 91.4400000 2.592000E+05
+football pitch 105.000000 2.976378E+05 approximate; pitch is not standardized
+rack unit U 0.0444500 126 1.75 inches
+hand h, hh 0.1016000 288 4 inches
+nose nse Smallest advantage a horse can win by; http://www1.drf.com/help/help_glossary.html
+Short head sh English term; http://www1.drf.com/help/help_glossary.html
+head hd http://www1.drf.com/help/help_glossary.html
+Short neck snk intermediate between a head and a neck; http://www1.drf.com/help/help_glossary.html
+neck nk 0.6096000 1,728 2 feet, a quarter of a length ; http://www1.drf.com/help/help_glossary.html
+horse length 1L 2.4384000 6,912 8 feet; http://www1.drf.com/help/help_glossary.html
+distance dst 73.1520000 207,360 240 feet; 30 lengths
+</tab>