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

SI Prefix

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

1 gram -> '1 g'

whereas

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 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.

• number pounds
  Generates a mass-value of n pounds.

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

• 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 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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