Defined Units¶
The units library comes with two sets of units predefined. They are all located in src/units/unit_definitions.hpp. The definitions come in two flavors a precise_unit and a regular unit. All the precise units are defined in the namespace units::precise
All the units are defined as a constexpr values. The choice of which units to define is somewhat arbitrary and guided by the authors experience and the origins of the library in power systems and electrical engineering in the US. Units that the author has actually encountered in work or life are included and in cases where there might be conflicts depending on the location preference was given to the US customary definition, though international systems take priority.
Listing of Units¶
The most common units are defined in the namespace units::precise and others are defined in subnamespaces.
Base Units¶
Most base units have two definitions that are equivalent
meter, m
kilogram, kg
second, s
Ampere, A
Kelvin, K
mol
candela, cd
currency
count
pu
iflag
eflag
radian, rad
Specialized units¶
Some specialized units are defined for use in conversion applications or for making handling string conversions a little easier
defunit - special unit that signifies conversion to any other units is possible
invalid - special unit that conversion has failed
error - an error unit
Numerical Units¶
Sometimes it is useful to have pure numerical units, often for multiplication with other units such as hundred*kg or something like that which becomes a single unit with 100 kg.
one
ten
hundred
percent (0.01)
infinite
nan
Also included in this category are SI prefixes deci, centi,milli, micro, nano, pico, femto, atto, zepto, yocto, ronto, quecto, deka, hecto, kilo, mega, giga, tera, peta, exa, hecto, zetta, yotta,rotta, quetta.
and SI data prefixes kibi, mebi, gibi, tebi, pebi, exbi, zebi, yobi
Derived SI Units¶
There are many units that used in combination with the SI system that are derived from the base units
hertz, Hz
volt, V
Pa (pascal, on some systems this is defined as something else so the definition(pascal) is skipped)
newton, N
joule, J
watt, W
coulomb, C
farad, F
siemens, S
weber, Wb
tesla, T
henry, H
lumen, lm
lux, lx
becquerel, Bq
gray, Gy
sievert, Sv
katal, kat
sr
Centimeter-Gram-Second system¶
The CGS system is a variant on the metric system. Units from the CGS system are included under the namespace units::precise::cgs.
eng
dyn
barye
gal
poise
stokes
kayser
oersted
gauss
debye
maxwell
biot
gilbert
stilb
lambert
phot
curie
roentgen
REM
RAD
emu
langley
unitpole
statC_charge
statC_flux
abOhm
abFarad
abHenry
abVolt
statV
statT
statHenry
statOhm
statFarad
Conventional Electrical Units¶
defined in namespace units::precise::conventional
volt90
ampere90
watt90
henry90
coulomb90
farad90
ohm90
Meter Gram Force System¶
defined in namespace units::precise::gm
pond
hyl
at
poncelet
PS
Meter Tonne Second system¶
Defined in namespace units::precise::MTS
sthene
pieze
thermie
Additional Time units¶
Defined in namespace units::precise::time, units marked with * are also defined in the units::precise.
min*
ms*
ns*
hr*
h*
day*
week
yr* (8760 hr)
fortnight
sday - sidereal day
syr - sidereal year
at - mean tropical year
aj - mean julian year
ag - mean gregorian year
year - aliased to median calendar year (365 days) which is the standard for SI
mos - synodal (lunar) month
moj - mean julian month
mog - mean gregorian month
International customary Units¶
These are traditional units that have some level of international definition Defined in namespace units::precise::i
grain
point
pica
inch
foot
yard
mile
league
hand
cord
board_foot
mil
circ_mil
A few units have short symbols defined in unit::precise in, ft, yd, mile. These alias to the international definition.
Avoirdupois units¶
Avoirdupois units are another common international standard of units for weight and volumes. The units are defined in units::precise::av
dram
ounce
pound
hundredweight
longhundredweight
ton
longton
stone
lbf
ozf
slug
poundal
A few common units have symbols defined in units::precise lb, ton, oz, lbf and these alias to the Avoirdupois equivalent.
Troy Units¶
Most commonly for precious metals a few units are defined in units::precise::troy, with a basis in the international grain.
pennyweight
oz
pound
United States Customary Units¶
These are traditional units defined in the United States, for survey or common usage. Defined in unit::precise::us.
foot
inch
mil
yard
rod
chain
link
furlong
mile
league
acre*
homestead
section
township
minim
dram
floz
tbsp
tsp
pinch
dash
shot
gill
cup
pint
quart
gallon
flbarrel - liquid barrel
barrel
hogshead
cord
fifth
A few US customary units are defined in specific namespaces to distinguish them from other forms US customary dry measurements are defined in units::precise::us::dry
pint
quart
gallon
peck
bushel
barrel
sack
strike
Some grain measures used in markets and commodities are defined in units::precise::us::grain. When commodities are a little more developed this will be defined with appropriate commodity included.
bushel_corn
bushel_wheat
bushel_barley
bushel_oats
Some survey units are defined in units::precise::us::engineers to distinguish them from others
chain
link
The unit gal (gallon) is also defined in units::precise since that is pretty common to use.
FDA and metric measures¶
The food and drug administration has defined some customary units in metric terms for use in medicine. These are defined in units::precise::metric Also included are some other customary units that have a metric definition.
tbsp
tsp
floz
cup
cup_uslegal
carat
Canadian Units¶
Some Canadian definitions of customary units defined in units::precise::canada
tbsp
tsp
cup
cup_trad
gallon
grain::bushel_oats
Australia Units¶
Traditional Australian units defined in units::precise::australia
tbsp
tsp
cup
Imperial or British Units¶
Traditional british or imperial units, defined in units::precise::imp.
inch
foot
thou
barleycorn
rod
chain
link
pace
yard
furlong
league
mile
nautical_mile
knot
acre
perch
rood
gallon
quart
pint
gill
cup
floz
tbsp
tsp
barrel
peck
bushel
dram
minim
drachm
stone
hundredweight
ton
slug
Apothecaries System¶
Used in pharmaceutical contexts the apothecaries system of units is defined in units::precise::apothecaries.
floz ( same as imperial version )
minim
scruple
drachm
ounce
pound
pint
gallon
metric_ounce
Nautical Units¶
Some units defined in context of marine travel defined in units::precise::nautical
fathom
cable
mile
knot
league
Japanese traditional Units¶
Some traditional Japanese units are included for historical interest in units::precise::japan
shaku
sun
ken
tsubo
sho
kan
go
cup
Chinese Traditional Units¶
Some traditional Chinese units are included for historical interest in units::precise::chinese
jin
liang
qian
li
cun
chi
zhang
Typographic units¶
Units used in typesetting and typography are included in units::precise::typographic Subsets of the units depending on the location are in subnamespaces
units::precise::typographic::american¶
line
point
pica
twip
units::precise::typographic::printers¶
point
pica
units::precise::typographic::french¶
point
ligne
pouce
didot
cicero
pied
toise
units::precise::typographic::metric¶
point
quart
units::precise::typographic::IN¶
l’Imprimerie nationale
point
pica
units::precise::typographic::tex¶
point
pica
units::precise::typographic::postscript¶
point
pica
units::precise::typographic::dtp¶
This is the modern standard or as close to such a thing as exists
point
pica
twip
line
units::precise::typographic¶
Values taken from dtp namespace
point
pica
Distance Units¶
Some additional distance units are defined in units::precise::distance
ly
au
au_old
angstrom
parsec
smoot
cubit
longcubit
arpent_us
arpent_fr
xu
Area Units¶
Some additional units defining an area units::precise::area
are
hectare
barn
arpent
Mass Units¶
Some additional units defining a mass units::precise::mass
quintal
ton_assay
longton_assay
Da
u
tonne
t is included in the units::precise namespace as a metric tonne
Volume Units¶
Some additional units defining a volume units::precise::volume
stere
acre_foot
drum
Angle Units¶
A few units defining angles are defined in units::precise::angle.
deg*
gon
grad
arcmin
arcsec
brad - binary radian (1/256 of a circle)
Directional Units¶
A few cardinal directional units are defined in units::precise::direction, these make use of the i_flag and a numerical value
east
north
south
west
Temperature Units¶
A few units related to temperature systems, defined in units::precise::temperature
celsius, degC*
fahrenheit, degF*
rankine, degR
reaumur
Pressure Units¶
Some units related to pressure are defined in units::precise::pressure
psi
inHg
mmHg
torr
inH2O
mmH2O
atm - standard atmosphere
att - technical atmosphere
Power Units¶
Some units related to power are defined in units::precise::power
hpE - electric Horsepower
hpI - international horsepower
hpS - steam horesepower
hpM - mechanical horsepower
the unit hp is aliased in the units::precise namespace to power::hpI
Energy Units¶
Some units related to energy are defined in units::precise::energy
kWh
MWh
eV
kcal
cal_4 - calorie at 4 deg C
cal_15 - calorie at 15 deg C
cal_28 - calorie at 28 deg C
cal_mean - mean calorie
cal_it - international table calorie
cal_th - thermochemical calorie
btu_th - thermochemical BTU
btu_39 - BTU at 39 deg C
btu_59 - BTU at 59 deg C
btu_60 - BTU at 60 deg C
btu_mean - mean BTU
btu_it - international table BTU
btu_iso - rounded btu_it
quad
tonc - cooling ton
therm_us
therm_br
therm_ec
EER - energy efficiency ratio
SG - specific gravity
ton_tnt
boe - barrel of oil equivalent
foeb
hartree
tonhour
tce - ton of coal equivalent
lge - liter of gasoline equivalent
in the units::precise namespace
btu = energy::but_it
cal = energy::cal_th
kWh = energy::kWh
MWh = energy::MWh
Power system Units¶
Some additional units related to power systems and electrical engineering in units::precise::electrical namespace
MW
VAR - W*i_flag
MVAR
kW
kVAR
mW
puMW
puV
puHz
MJ
puOhm
puA
kV
mV
mA
Equation type Units¶
Equation units are explained more thoroughly in Equation Units Some of the specific common equation units are defined in the namespace units::precise::log.
neper
logE - natural logarithm
neperA - neper of amplitude unit
neperP - neper of a power unit
logbase10
bel
belP - bel of a power based unit
dBP
belA - bel of an amplitude based unit
dBA - dB of an amplitude based unit
logbase2
dB
neglog10
neglog100
neglog1000
neglog50000
B_SPL
B_V
B_mV
B_uV
B_10nV
B_W
B_kW
dB_SPL
dB_V
dB_mV
dB_uV
dB_10nV
dB_W
dB_kW
dB_Z - radar reflectivity
BZ - radar reflectivity
Clinical Units¶
Units related to clinical medicine in namespace units::precise::clinical.
pru
woodu
diopter
prism_diopter
mesh
charriere
drop
met
hounsfield
Laboratory Units¶
Units used in laboratory settings in namespace units::precise::laboratory.
svedberg
HPF
LPF
enzyme_unit
IU
arbU - arbitrary unit
IR - index of reactivity
Lf - Limit of flocculation
PFU
pH
molarity
molality
Data Units¶
Units related to computer data and storage in units::precise::data
bit*
nibble
byte
kB*
MB*
GB*
kiB
MiB
GiB
bit_s - Shannon bit for information theory
shannon
hartley
ban
dit
deciban
nat
trit
digits
B is defined as byte in units::precise
Computation units¶
Units related to computation units::precise::computation.
flop
flops
mips
Special units¶
Some special units that were not otherwise characterized in namespace units::precise::special.
ASD - amplitude spectral density
moment_magnitude - moment magnitude for earthquake scales (related to richter scale)
moment_energy
sshws - saffir simpson hurricane wind scale
beaufort - Beaufort wind scale
fujita - Fujita scale for tornados
mach - mach number(multiplier of the speed of sound)
rootHertz - square root of Hertz, this is a special handling unit that triggers some specific behavior to handle it.
rootMeter - square root of meter, this is a special handling unit that triggers some specific behavior to handle it.
Other Units¶
General purpose other units not otherwise categorical in namespace units::precise::other
ppm - part per million
ppb - part per billion
candle
faraday
rpm* - revolution per minute
CFM - cubic feet per minute
MegaBuck - $1,000,000
GigaBuck - $1,000,000,000
Climate Units¶
Units related to climate in namespace units::precise::climate
gwp - global warming potential
gtp - global temperature potential
Speed Units¶
mph and mps are defined in units::precise since they are pretty common
Units in the units namespace¶
Regular units are defined in the units namespace. The general rule is that any units with a definition directly in units::precise has an analog nonprecise unit in the units namespace. One addition is that any unit defined in precise::electrical also is defined in units this has to do with the origins of the library in power systems.