PhysicalValues/en

Expecco supports values with units to represent physical values such as length, acceleration, area, volume, mass, temperature etc.

Physical values are useful for a nicer presentation of values (eg. in a report) and to convert between unit systems (eg. metric vs. imperial vs. US).

Physical values are implemented by the underlying Smalltalk system and can be used in JavaScript and Smalltalk elementary blocks. Similar public domain packages are available for Node and Python actions - these have to be installed with "rpm"or "pip".

Base Units

All base units are measured in their corresponding SI standard units and print with an appropriate scaling prefix.

For example, a mass, which has a base unit of kilogram ("kg") will print itself as "kg', 'mg', 'µg' etc. depending on its magnitude. Explicit converters can be used to enforce a particular unit printing (eg. if you insist on printing a mass in pounds, in grams, etc.). See examples below on how those converters affect the printout of a value.

Base units are:

s	second	    time
m	metre	    length
kg	kilogram    mass
A	ampere	    electric current
K	kelvin	    temperature
mol	mole	    amount of substance
cd	candela	    luminous intensity

Derived Units

Additional derived units are:

V      volt                voltage
Hz     hertz               frequency
m/s    meter per second    speed, velocity
m/s²   m/s per second      acceleration
m²     square meter        area
m³     cubic meter         volume
pa     pascal              pressure
w      watt                power
N      newton              force
J      joule               energy
Ω      ohm                 electric resistance
C      coulomb             electric charge

SI Prefix

Numbers can be scaled by an SI prefix message. For example, without si prefix:

1 gram -> '1 g'

whereas with a 'micro' prefix:

1 micro gram -> '1 µg'

and:

1 hecto liter -> '100 liter'

Possible scaling prefixes are:

yocto   1E-24   1 / 1000000000000000000000000 
zepto   1E-21   1 / 1000000000000000000000 
atto    1E-18   1 / 1000000000000000000
femto   1E-15   1 / 1000000000000000
pico    1E-12   1 / 1000000000000
nano    1E-9    1 / 1000000000
micro   1E-6    1 / 1000000
milli   1E-3    1 / 1000
centi   1E-2    1 / 100
deci    1E-1    1 / 10
deca    1E+1    10
hecto   1E+2    100
kilo    1E+3    1000
mega    1E+6    1000000
giga    1E+9    1000000000
tera    1E+12   1000000000000
peta    1E+15   1000000000000000
exa     1E+18   1000000000000000000
zetta   1E+21   1000000000000000000000
yotta   1E+24   1000000000000000000000000

Mass

Mass is measured in units of kilogram. The following operations return an instance of a mass (i.e. a value with a unit of "Mass"):

• number kiloGram
  Generates a mass-value of n kilograms. Same as n kilo gram.

• number gram
  Generates a mass-value of n grams.

• number milliGram
  Generates a mass-value of n milligrams. Same as n milli gram.

• number microGram
  Generates a mass-value of n micrograms. Same as n micro gram.

• number pounds
  Generates a mass-value of n pounds. A pound is 453.59237 gram.

Conversion

• aMass asGrams
  Returns the original mass but enforces explicit printing in grams.

• aMass asMilliGrams
  Enforces explicit printing in milligrams.

• aMass asMicroGrams
  Enforces explicit printing in micrograms.

• aMass asKiloGrams
  Enforces explicit printing in kilograms.

• aMass asPounds
  Enforces explicit printing in pounds.

Length

Length is measured in meters.

• number meter
  Generates a length-value of n meters.

• number centiMeter
  Generates a length-value of n centimeters. Same as n centi meter.

• number milliMeter
  Generates a length-value of n millimeters. Same as n milli meter.

• number microMeter
  Generates a length-value of n micrometers. Same as n micro meter.

• number nanoMeter
  Generates a length-value of n nanometers. Same as n nano meter.

• number kiloMeter
  Generates a length-value of n kilometers. Same as n kilo meter.

• number inch
  Generates a length-value of n inches. An inch is 25.4 mm.

• number feet
  Generates a length-value of n feet. A foot is 0.3048 m.

• number landMiles
  Generates a length-value of n landMiles. A landMile is 5280 feet or 1609.344 m.

• number nauticalMiles
  Generates a length-value of n nauticalMiles. A nauticalMile is 1852 m.

Conversion

• aLength asMeters
  Returns the original length but enforces explicit printing in meters.

• aLength asMilliMeters
  Enforces explicit printing in millimeters.

• aLength asMicroMeters
  Enforces explicit printing in micrometers.

• aLength asKiloMeters
  Enforces explicit printing in kilometers.

• aLength asInches
  Enforces explicit printing in inches.

• aLength asFeet
  Enforces explicit printing in feet.

• aLength asYards
  Enforces explicit printing in yards.

• aLength asFeetAndInches
  Enforces explicit printing in feet and inches (in rounded to 4 digits).

Temperature

• number kelvin
  Generates an temperature-value of n Kelvin.

• number degreesCelcius
  Generates an temperature-value of n degrees Celsius.

• number degreesFahrenheit
  Generates an temperature-value of n degrees Fahrenheit.

Frequency

• number hertz
  Generates an frequency-value of n hertz.

• number kiloHertz
  Generates an frequency-value of n kilohertz.

• number megaHertz
  Generates an frequency-value of n megahertz.

• number gigaHertz
  Generates an frequency-value of n gigahertz.

Energy

• number joule
  Generates an energy-value of n joule.

• number kiloJoule
  Generates an energy-value of n kilojoule.

• number megaJoule
  Generates an energy-value of n megajoule.

• number kiloWattHours
  Generates an energy-value of n kiloWattHours.

Power

• number watt
  Generates a power-value of n watt.

• number kiloWatt
  Generates a power-value of n kiloWatt.

• number megaWatt
  Generates a power-value of n megaWatt.

• number gigaWatt
  Generates a power-value of n gigaWatt.

Area

• number squareMeter
  Generates an area-value of n square meters.

• number hectare
  Generates an area-value of n hectares.

Volume

• number liter
  Generates an volume-value of n liters.

• number milliLiter
  Generates a length-value of n milliliters.

Mass Density

This is a derived unit, which is generated when dividing a mass by a volume; eg:

10 kiloGram / 1 liter 

gives

'10000 kg / m³'

Examples

Smalltalk code + printed representation.

1 kiloGram + 10.0 gram -> '1.01 kg' 

10 gram -> '10 g'

10 gram asKiloGrams -> '0.01 kg'

10 gram asMilliGrams -> '10000 mg'

1 microGram -> '1 µg'

1 micro gram -> '1 µg'

1 pound -> '453.59237 g'

1 pound asKiloGrams -> '0.45359237 kg'

1 pound asPounds -> '1.0 lb' 

1 kiloGram asPounds -> '2.20462262184878 lb'

1 micro inch -> '25.4 nm'

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