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 notation. 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

SI Prefix

Numbers can be scaled by an SI prefix message. For example:

1 gram -> '1 g'

whereas

1 micro gram -> '1 µg'

Possible scaling names are: 'atto', 'femto', 'pico', 'nano', 'micro', 'milli', 'kilo', 'mega', 'giga', 'tera', 'peta' (among others).

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 number kilo gram.

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

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

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

Conversion

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

• aMass asMilliGrams
  Enforces explicit printing in milligrams.

• aMass asKiloGrams
  Enforces explicit printing in kilograms.

Length

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

• number milliMeter
  Generates a length-value of n millimeters.

• number microMeter
  Generates a length-value of n micrometers.

• number kiloMeter
  Generates a length-value of n kilometers.

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

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 micro inch -> '25.4 nm'

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