vCalc units are implemented in objects known as Amounts.  Amounts have a value, an associate unit and a powerful set of functions.  Parameters are designated as Amounts (having units) in the Equation Editor Algorithm Tab in both the algorithm code and in the user input UI where you can designate units for the input parameters.

To create an input parameter, you have to define a parameter using the ".args" extension.  See the following example:

                      def h = args.h   //create an input parameter named h
                      def w = args.w  //create an input parameter named w

Once you've entered the two lines of code, vCalc's Equation Editor will pop-up two lines at the bottom of the algorithm with options associated with the input parameters (h and w in the example above).  In the Input Parameter window, you can select units for the parameter.  You can select a specific class (e.g. length) and unit type (e.g. meters), or you can select "Any" from a class and the default will be used. In any case, the user can toggle to different units in the class (i.e. to compatible units)

Now that you have parameter that are amounts, you have a lot of functions you can employ.  These include the following:

• .to()  converts your amount to a compatible unit. For example, the two lines that follow convert h and w to centimeters and kilograms respectively.
  • def h = #h.to("cm").estimatedValue convert to cm then throw away units
  • def w = #w.to("kg").estimatedValue convert to kg then throw away units
• ."unit"  does not convert to a unit, but directly turns a number into an Amount with the units designated.  For example, the next line makes parameter B an amount with the value of BSA and the units meters squared.
  • B = BSA."m^2"
• .estimatedValue takes an amount and captures its value without units, and creates just a real number.  Sometimes this is very important, because there are many algorithms that violate unit operations. For example fractional exponents are troublesome to Amounts.  A common medical formula for the Body Surface area uses such fractional exponents (BSA = 0.008883 * h^0.663 * w^0.444) where h and w are height in centimeters and weight in kilograms respectively and yet the results are in square meters of skin. Also, some complex algorithms with numerous conditional statements (if, switch, etc) are hard for the unit handling algorithm to keep track of the resulting units. In such cases, we often convert to ( .to() ) a unit that we use as the base and then convert the Amount to a real number using .estimatedValue for the rest of the algorithm, and then rely on the programmer to cast the real back into the correct unit as in the example just above this. The following line takes an input parameter "Vm", converts it to cubic meters, and then treats it like a real number in parameter X.
  • def h = args.h.to("cm").estimatedValue  // Convert h to centimeters and then throw away the units.
  • def w = args.w.to("kg").estimatedValue // Convert w to kilograms and then throw away the units.
  • def BSA = 0.008883 * h**(0.663 ) * w**(0.444)
  • return BSA
• .getUnit() returns the units of the Amount.  For example:  return z.to(h.getUnit())  this converts z to the units of h

The list of units are as follows:

Table of named units

	Quantity Type=		Std Unit		Named Units
	Acceleration		m/s²		m/s², ft/s², grav
	Amount Of Substance		mol		mol, atom, osmole
	Angle		rad		rad, centiradian, °, grade, ', rev, \"
	Angular Acceleration		rad/s²		rad/s², rad/h², rad/min², °/h², °/min², °/s²
	Angular Velocity		rad/s		rad/s, rad/day, rad/h, rad/min, °/day, °/h, °/min, °/s, rev/s, rpm, rev/h, rev/day
	Area		m²		m², µm², mm², cm², km², in², ft², yd², mi², acre, a, ha
	Catalytic Activity		kat		kat
	Concentration		mol/m3		mol/m3, mol/L
	Data Amount		bit		bit, Mb, byte, KB, MB, GB,TB,PB
	Data Rate		bit/s		bit/s, bit/min, bit/day, MB/s, Mb/min, Mb/h, Mb/day, bytes/s, byte/min, byte/h, byte/day, KB/s, KB/min, KB/h, KB/day, MB/s, MB/min, MB/h, MB/day, GB/s, GB/min, GB/h, GB/h, GB/day, TB/s, TB/min, TB/h, TB/day, PB/s, PB/min, PB/h, PB/day
	Dimensionless				%, dB (''real'' may be used as alias for empty string unit)
	Duration		s		s, µs, ns, ms, min, h, day, week, month, year, decade, century, day_sidereal, year_calendar, year_sidereal
	Dynamic Viscosity		''P·s''		kg/(m·s), g/(cm·s)
	Electric Capacitance		F		F, pF, µF, mF, kF
	Electric Charge		C		C, Fr, Fd, e
	Electric Conductance		S		S
	Electric Current		A		Gi, A, mA, µA, nA
	Electric Field		N/C		N/C, kgf/C, lbf/C, V/m, V/ft, V/in
	Electric Inductance		H		H, mH, nH
	Electric Potential		V		V
	Electric Resistance		Ω		Ω,mΩ,kΩ	"Ohm"
	Energy		J		J, ft_lbf, mJ, W_s, N_m, kWh, MWh, GWh, TWh, feV, neV, µeV, meV, keV, MeV, peV, hartree, erg, eV, cal, kcal, Mcal, BTU
	Enthalpy		J/mol		J/mol, kJ/mol, BTU/mol, eV/mol, erg/mol
	Fluid Resistance		Pa·s/L		Pa·s/L, Pa·min/L, Pa·s/mL, Pa·min/mL, Pa·s/m³, Pa·min/m³, Pa·s/cm³, Pa·min/cm³, mmHg·s/L, mmHg·min/L, mmHg·s/mL, mmHg·min/mL, mmHg·s/cm³, mmHg·min/cm³
	Force		N		N, dyn, kgf, lbf, tonne_force, short_ton_force, long_ton_force
	Frequency		Hz		Hz, kHz, MHz, GHz, THz, PHz, Ehz, perSec, perMin, perHr, perDay, perWk, perYr
	Heat Capacity		J/K		J/K, J/℃, J/°F
	Illuminance		lx		lx, La, W/cm2, W/m2
	Kinematic Viscosity		''m²/s''		cm²/s
	Length		m		m, nm, µm, mm, cm, km, in, ft, yd, mi, nmi, Å, mil, pixel, pt, foot_survey_us, fathom, au, light_second, light_munite, light_hour, light_day, ly, pc, kly, Mpc
	Length per Volume		mpg		mpg,km/L
	Luminous Flux		lm		lm
	Luminous Intensity		cd		cd
	Magnetic Field Strength		A/m		A/m
	Magnetic Flux		Wb		Wb, Mx
	Magnetic Flux Density		T		G, T
	Mass		kg		kg, mg, g, oz, lb, ton_us, t, ton_uk, me, u, gr, ct, dwt, troy_ounce, Earth_Mass, Jupiter_Mass, Solar_Mass
	Mass Flow Rate		kg/s		kg/s, kg/min, kg/h, g/s, lb/s, lb/min, lb/h
	Molar Mass		g/mol		g/mol, kg/mol, kg/kmol, mg/mol, oz/mol, lb/mol
	Moment of Inertia		kg·m²		kg·m², g·m², lb·ft², oz·in²
	Momentum		kg⋅m/s		kg⋅m/s
	Money		USD		USD, AUD, BRL, CAD, CHF, CNY, EUR, GBP, INR, JPY, MXN, RUB, ZAR
	Money per Area		USD/in2		USD/in2, USD/ft2, USD/yd2, EUR/cm², EUR/m², EUR/km², GBP/cm², GBP/m², GBP/km², JPY/cm², JPY/m², JPY/km², INR/cm², INR/m², INR/km², CNY/cm², CNY/m², CNY/km², RUB/cm², RUB/m², RUB/km²
	Money Per Energy		USD/J		USD/J, USD/kWh, USD/MWh, USD/GWh, USD/TWh, EUR/kWh, EUR/MWh, EUR/GWh, EUR/TWh, INR/kWh, INR/MWh, INR/GWh, INR/TWh, RUB/kWh, RUB/MWh, RUB/GWh, RUB/TWh
	Money Per Length		USD/in		USD/in, USD/ft, USD/mi, EUR/cm, EUR/m, EUR/km, GBP/cm, GBP/m, GBP/km, JPY/cm, JPY/m, JPY/km, INR/cm, INR/m, INR/km, CNY/cm, CNY/m, CNY/km, RUB/cm, RUB/m, RUB/km
	Money Per Mass		USD/oz		USD/oz, USD/lb, USD/ton_us, EUR/g, EUR/kg, EUR/t, GBP/g, GBP/kg, GBP/t, CAD/g, CAD/kg, JPY/g, JPY/kg, JPY/t, INR/g, INR/kg, INR/t, CNY/g, CNY/kg, CNY/t, RUB/g, RUB/kg, RUB/t
	Money Per Time		USD/h		USD/s, USD/min, USD/h, USD/day, CAD/s, CAD/min, CAD/h, CAD/day, EUR/s, EUR/min, EUR/h, EUR/day, GBP/s, GBP/min, GBP/h, GBP/day, MXN/s, MXN/min, MXN/h, MXN/day, JPY/s, JPY/min, JPY/h, JPY/day, INR/s, INR/min, INR/h, INR/day, CNY/s, CNY/min, CNY/h, CNY/day, RUB/s, RUB/min, RUB/h, RUB/day
	Money Per Volume		USD/oz_liquid		SD/oz_liquid, USD/qt, USD/gal, USD/ft³, USD/bbl, CAD/cL, CAD/L, CAD/m³, CAD/bbl, EUR/cL, EUR/L, EUR/m³, EUR/bbl, GBP/cL, GBP/L, GBP/m³, GBP/bbl, MXN/cL, MXN/L, MXN/m³, MXN/bbl, JPY/cL, JPY/L, JPY/m³, JPY/bbl, INR/cL, INR/L, INR/m³, INR/bbl, CNY/cL, CNY/L, CNY/m³, CNY/bbl, RUB/cL, RUB/L, RUB/m³, RUB/bbl
	Permeability		d		d, md, µd
	Power		W		W, hp, mW, kW, MW, GW, TW, BTU/h
	Pressure		Pa		Pa, mPa, kPa, MPa, mmHg, inHg, mbar, bar, atm, N/mm², N/cm², lbf/in²
	Radiation Dose Absorbed		Gy		rem, Sv, Gy, rd
	Radiation Dose Effective		Sv		rem, Sv, Gy, rd
	Radioactive Activity		Bq		Bq, Ci
	Solid Angle		sr		sr, sphere
	Stress		N/m2		N/m², N/cm², N/mm², kN/cm², kN/mm², psi_stress, lbf/ft², short_ton_force/in², short_ton_force/ft², long_ton_force/in², long_ton_force/ft²
	Surface Energy		N/m		N/m, lbf/in, lbf/ft
	Temperature		K		°R, K, °F, ℃
	Torque		''N·m''		J, erg, eV, ft_lbf, mJW_s, N_m, kWh, MWh, GWh, TWh, feV, neV, μeV, meV, keV, MeV, peV, hartree, cal, kcal, Mcal, BTU
	Velocity		m/s		m/s, m/min, mm/s, cm/s, km/s, km/min, km/h, mph, in/s, in/min, in/h, ft/s, ft/min, ft/h, kn, Mach, c
	Volume		m³		gallon_uk, oz_liquid_uk, km³, mi³, ft³, gallon_dry_us, L, km3, bu, mm³, gal, yd³, m³, mm³, in³, cm³, mL, oz_liquid, ac⋅ft, smidgen, pinch, dash, tsp, tbsp, cup, pint, qt, drop, bbl
	Volumetric Density		kg/m³		kg/m³, lb/ft³, g/cm³, t/m³, ton_us/yd³, oz/in³, g/mL, kg/L, g/m³
	Volumetric Flow Rate		m³/s		m³/s, L/s, L/min, L/h, mL/s, mL/min, mL/h, qt/s, qt/min, qt/h, gal/s, gal/min, gal/h, drop/min, bbl/min, bbl/h, bbl/day, ft³/min, ft³/h, ft³/day, m³/min, m³/h, m³/day

Unit Labels

SI Labels

All SI Units are labeled only by their standard symbol (e.g. ''Meter'' is labeled as ''m'', with the exception of the following additional labels intended to ease ascii use.

	System ID		Label		Notes
	SI.OHM		Ohm		may be used in place of ''Ω''
	SI.CELSIUS		Celsius		may be used in place of ''°C'' or ''℃''

Additionally, as discussed above in SI Prefixes, it is valid to reference any SI  unit with a standard SI prefix attached.

NonSI Labels

	System ID		Label
	NonSI.PERCENT		%
	NonSI.DECIBEL		dB
	NonSI.G		grav
	NonSI.ATOM		atom
	NonSI.REVOLUTION		rev
	NonSI.DEGREE_ANGLE		°
	NonSI.DEGREE_ANGLE		degree_angle
	NonSI.MINUTE_ANGLE		'
	NonSI.SECOND_ANGLE		\"
	NonSI.CENTIRADIAN		centiradian
	NonSI.GRADE		grade
	NonSI.ARE		a
	NonSI.HECTARE		ha
	NonSI.BYTE		byte
	NonSI.MINUTE		min
	NonSI.HOUR		h
	NonSI.DAY		day
	NonSI.WEEK		week
	NonSI.YEAR		year
	NonSI.MONTH		month
	NonSI.DAY_SIDEREAL		day_sidereal
	NonSI.YEAR_SIDEREAL		year_sidereal
	NonSI.YEAR_CALENDAR		year_calendar
	NonSI.E		e
	NonSI.FARADAY		Fd
	NonSI.FRANKLIN		Fr
	NonSI.GILBERT		Gi
	NonSI.ERG		erg
	NonSI.ELECTRON_VOLT		eV
	SI.KILO(NonSI.ELECTRON_VOLT)		keV
	SI.MEGA(NonSI.ELECTRON_VOLT)		MeV
	SI.GIGA(NonSI.ELECTRON_VOLT)		GeV
	NonSI.LAMBERT		La
	NonSI.FOOT		ft
	NonSI.FOOT_SURVEY_US		foot_survey_us

vCalc Custom Labels

	System ID		Label
	FATHOM		fathom
	BUSHEL		bu
	QUART_US		qt
	PINT_US		pint
	CUP		cup
	TABLESPOON		tbsp
	TEASPOON		tsp
	DASH		dash
	PINCH		pinch
	SMIDGEN		smidgen
	CARAT		ct
	GRAIN		gr
	TROY_OUNCE		troy_ounce
	PENNY_WEIGHT		dwt
	BTU		BTU
	HARTREE		hartree
	HARTREE		E_h
	CAL		cal
	TONNE_FORCE		tonne_force
	LONG_TON_FORCE		long_ton_force
	SHORT_TON_FORCE		short_ton_force
	PER_SEC		perSec
	PER_MIN		perMin
	PER_HOUR		perHr
	PER_DAY		perDay
	PER_WEEK		perWk
	PER_YEAR		perYr
	BPM		BPM
	REV_PER_MIN		rpm
	ACRE		acre
	MIL		mil
	KILOLIGHTYEAR		kly
	MILLIBAR		mbar
	DARCY		d
	MICRODARCY		µd
	MILLIDARCY		md
	MILLIOHM		mOhm
	KILOOHM		kOhm
	SI.MICRO(SI.METER)		microm
	NonSI.DEGREE_ANGLE		degree_angle
	Dimensionless.UNIT		(empty string) or "real"