quantify 0.15.0

Type-safe unit converter. Convert length, mass, temperature, speed, energy, pressure and 20+ physical quantities with compile-time safety, elegant extension syntax and constants.

Changelog

All notable changes to the quantify package will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

0.15.0

2026-02-23

Added

• New Quantity: TemperatureDelta — a dedicated type for temperature changes (intervals), distinct from absolute Temperature points.

  • TemperatureDeltaUnit enum with four linear units: kelvinDelta, celsiusDelta, fahrenheitDelta, rankineDelta.
  • Factors: kelvinDelta = celsiusDelta = 1.0 K; fahrenheitDelta = rankineDelta = 5/9 K.
  • Full arithmetic: TemperatureDelta + TemperatureDelta, - TemperatureDelta, * scalar, / scalar.
  • Convenience extensions on num: 20.celsiusDelta, 18.fahrenheitDelta, 10.kelvinDelta, 9.rankineDelta.
  • Value getters on TemperatureDelta: inKelvinDelta, inCelsiusDelta, inFahrenheitDelta, inRankineDelta and as* conversion variants.
  • Interop extension TemperatureDeltaTemperatureInterop providing delta.addTo(temperature) for the commutative form of heating.
  • Available via package:quantify/quantify.dart or the new granular package:quantify/temperature_delta.dart.

• Temperature.asDelta getter — converts an absolute temperature to a TemperatureDelta relative to absolute zero (always in kelvinDelta). Useful for formulas that require a Kelvin scalar magnitude, such as the ideal gas law or Boltzmann energy calculations.

• Temperature.ratioTo(Temperature other) — replaces operator / for temperature ratios. Always converts both operands to Kelvin before dividing, ensuring thermodynamic validity regardless of the input scale (e.g. 300.celsius.ratioTo(200.celsius) gives 573.15 / 473.15, not 3/2). Throws ArgumentError if the divisor is absolute zero.

• Temperature.operator +(TemperatureDelta delta) — adds a delta to an absolute temperature, returning a new Temperature in the same unit. Models heating.

• Temperature.subtract(TemperatureDelta delta) — subtracts a delta from an absolute temperature, returning a new Temperature. Named method (not an operator) because operator - is reserved for Temperature - Temperature. Equivalent to temp + (delta * -1.0).

Changed — Breaking

• Temperature.operator -(Temperature other) now returns TemperatureDelta (previously returned double). The result's unit mirrors the LHS unit (e.g. subtracting two Celsius temperatures yields a celsiusDelta).

  Migration: replace double diff = t2 - t1; with double diff = (t2 - t1).inKelvinDelta; (or .inCelsiusDelta, etc.).

• Temperature.operator / removed. Use temperature.ratioTo(other) instead. The new method always uses Kelvin, making the ratio physically meaningful for all input scales.

  Migration: replace t2 / t1 with t2.ratioTo(t1).

• EngineeringConstants.thermalExpansion now accepts TemperatureDelta instead of Temperature. The previous signature would apply the Kelvin affine offset to what should be a plain delta, producing results up to ~14× too large for typical Celsius inputs.

  Migration: replace 20.celsius with 20.celsiusDelta, or pass the result of t2 - t1 directly (it is now a TemperatureDelta).

• EngineeringConstants.conductiveHeatTransfer now accepts TemperatureDelta instead of Temperature, for the same reason.

  Migration: replace const Temperature(10, TemperatureUnit.kelvin) with 10.kelvinDelta.

Fixed

• thermalExpansion and conductiveHeatTransfer no longer misinterpret a temperature difference as an absolute temperature, eliminating a silent calculation error where 20.celsius was internally treated as 293.15 K.

0.14.2

2026-02-20

Fixed

• fix: correct markdown formatting

0.14.1

2026-02-20

Fixed

• Quick Start code example had an undeclared variable that prevented compilation.
• Removed unused duplicate imports in mass conversion factors.
• Example project SDK constraint now matches the main package requirement (>=3.5.0).

Changed

• Standardized barrel file exports for density and specific_energy to match other quantities. Removed unintended public export of internal factor constants.

0.14.0

2026-02-11

Added

• Energy: International Table (IT) Calorie Variants:
  • Added EnergyUnit.calorieIT and EnergyUnit.kilocalorieIT for International Table calorie (4.1868 J).
  • New extensions: .calIT, .kcalIT, .caloriesIT, .kilocaloriesIT for creating Energy instances.
  • New getters: .inCaloriesIT, .inKilocaloriesIT, .asCaloriesIT, .asKilocaloriesIT for conversions.
  • Existing calorie and kilocalorie units continue to use the thermochemical calorie (4.184 J) as the IUPAC/ISO standard.

Changed

• Improved Pressure Unit Conversion Accuracy:
  • Distinguished between Torr and mmHg (millimeter of mercury) for higher precision.
    • Torr is now defined as exactly 1/760 of a standard atmosphere (101325/760 Pa).
    • mmHg uses the conventional value based on actual mercury density at 0°C (133.322387415 Pa).
    • The difference is approximately 0.000019 Pa, significant for high-precision scientific applications.
  • Updated inHg (inch of mercury) conversion to be based on mmHg rather than Torr for consistency with scientific standards (NIST SP 811).

0.13.0

2026-01-12

• New Quantity: Density: Support for kg/m³, g/cm³, g/mL.
• New Quantity: Specific Energy: Support for J/kg, Wh/kg, kWh/kg, kJ/kg.
• Volume: Added centiliter (cl) unit.
• Improved: Complete unit tests for new quantities.

0.12.0

2025-08-11

Added

• Major Feature: Comprehensive Constants Library.
  • A library of over 100 type-safe constants, organized into three categories: PhysicalConstants, AstronomicalConstants, and EngineeringConstants.
  • Constants are represented as Quantity objects wherever possible (e.g., PhysicalConstants.speedOfLight is a Speed object, AstronomicalConstants.standardGravity is an Acceleration object).
  • Added convenience methods for common scientific and engineering formulas, such as PhysicalConstants.photonEnergy(), AstronomicalConstants.escapeVelocity(), and EngineeringConstants.mechanicalStress().
  • Constants are accessible via a new, separate import: package:quantify/constants.dart.

0.11.0

2025-07-27

Changed

• Conceptual Refinement of Frequency and AngularVelocity:
  • Frequency is now the comprehensive quantity for all periodic units (inverse time, T⁻¹), including rotational rates.
  • AngularVelocity remains a distinct, specialized type for rotational mechanics to ensure semantic type safety.

Added

• Frequency Unit Expansion: Added rad/s (radian per second) and deg/s (degree per second) to Frequency.
• Interoperability Between Frequency and AngularVelocity:
  • Added a safe .asFrequency getter to AngularVelocity for direct conversion to a Frequency object.
  • Added a guarded .asAngularVelocity getter to Frequency that only converts compatible rotational units (rpm, rad/s, Hz, etc.) and throws an UnsupportedError for non-rotational units (like bpm or MHz), preventing logical errors in calculations.

0.10.0

2025-07-26

• New Quantities: Energy and Power

  • Added the Energy quantity with common units (J, kJ, MJ, kWh, kcal, eV, Btu).
  • Added the Power quantity with a comprehensive set of SI, engineering, and CGS units (W, kW, MW, GW, hp, PS, Btu/h, erg/s).

• Expanded Unit Coverage

  • Added new units to Acceleration (cm/s²), Force (gf, pdl), and ElectricCharge (mAh, statC, abC)

0.9.0

2025-07-22

• Added relational operators (>, <, >=, <=) for all quantities. Comparisons are now more readable (e.g., 1.m > 99.cm).
• Added isEquivalentTo() method for explicit magnitude equality checks (e.g., 1.m.isEquivalentTo(100.cm)).

0.8.0

2025-07-22

• New Derived Quantities
  • Frequency with units (Hz, MHz, GHz, THz, rpm, etc.).
  • ElectricCharge with units (C, Ah, e, µC, etc.).
  • SolidAngle with units (sr, deg², sp).

0.7.0

2025-07-16

• New Derived Quantity
  • Area with units (m², km², ha, acre, yd², ft², etc.).
  • Volume with comprehensive SI, US customary, and cooking units (m³, L, gal, fl-oz, tsp, etc.).

0.6.0

2025-07-05

• New Derived Quantities
  • Speed: Added m/s, km/h, mph, kn, ft/s.
  • Acceleration: Added m/s², g (standard gravity), km/h/s.
  • Force: Added N (Newton), lbf, dyn, kgf, kN.

0.5.0

2025-06-29

Added

• Expanded Unit Coverage:

  • Length: Added Mm (megametre) and Gm (gigametre).
  • Mass: Added Mg (megagram) and Gg (gigagram).
  • Time: Added full range of SI prefixes (Gs to cs) and calendar units (fortnight, decade, century).
  • ElectricCurrent: Added CGS units statA (statampere) and abA (abampere/biot).

• Granular Exports: Added separate library entry points (e.g., package:quantify/length.dart) to allow for explicit imports and prevent namespace conflicts.

0.4.0

2025-06-23

Added

• New Quantity: Angle

  • Angle quantity
  • AngleUnit:
    • radian (rad): The SI-derived unit, used as the base for conversions.
    • degree (°): The most common unit for angles.
    • gradian (grad): Unit used in surveying (400 grad in a circle).
    • revolution (rev): Represents a full circle or turn.
    • arcminute ('): High-precision unit (1/60 of a degree).
    • arcsecond ("): High-precision unit (1/60 of an arcminute).
    • milliradian (mrad): Common in optics and ballistics.
  • Standard arithmetic operators (+, -, *, /) for Angle.

• New Quantity: AngularVelocity

  • AngularVelocity quantity - represents rotational speed.
  • AngularVelocityUnit:
    • radianPerSecond (rad/s): The SI-derived unit.
    • degreePerSecond (°/s).
    • revolutionPerMinute (rpm): A widely used unit for rotational speed.
    • revolutionPerSecond (rps).
  • Standard arithmetic operators for AngularVelocity.

0.3.0

2025-06-21

Added

• Expanded Unit Coverage:
  • Length:
    • SI Prefixes: hm (hectometer), dam (decameter), dm (decimeter), μm (micrometer), nm (nanometer), pm (picometer), fm (femtometer).
    • Astronomical: AU (astronomical unit), ly (light year), pc (parsec).
    • Special: Å (ångström).
  • Mass:
    • SI Prefixes: hg (hectogram), dag (decagram), dg (decigram), cg (centigram), μg (microgram), ng (nanogram).
    • Imperial/US: short ton, long ton.
    • Special: u (atomic mass unit), ct (carat).
  • Time:
    • SI Prefixes: μs (microsecond), ns (nanosecond), ps (picosecond).
    • Calendar: wk (week), mo (month), yr (year).
  • Temperature:
    • Absolute Scale: °R (rankine).

0.2.0

2025-06-16

Added

• New SI Base Quantity Types (completing all 7 SI base units):
  • Mass:
    • Mass class and MassUnit enum (kg, g, mg, t (tonne), lb, oz, st (stone), slug).
  • Amount of Substance (Molar Amount):
    • MolarAmount class and MolarUnit enum (mol, mmol, µmol, nmol, pmol, kmol).
  • Electric Current:
    • Current class and CurrentUnit enum (A, mA, µA, nA, kA).
  • Luminous Intensity:
    • LuminousIntensity class and LuminousIntensityUnit enum (cd, mcd, kcd).

0.1.0

2025-06-12

Added

• Initial Release of quantify v0.1.0
• Core Functionality:
  • Type-safe Quantity base class for representing physical quantities with a value and a unit.
  • Unit interface for defining conversion factors and symbols.
  • Immutable Quantity objects.
  • double precision for quantity values.
  • Elegant API with extension methods on num for quantity creation (e.g., 10.m, 20.celsius).
  • Extension methods on Quantity for easy value retrieval in target units (e.g., length.inKm) and for obtaining new Quantity objects in target units (e.g., length.asKm).
  • Configurable toString() method on Quantity objects supporting:
    • Conversion to a targetUnit before formatting.
    • Fixed fractionDigits.
    • Option to showUnitSymbol.
    • Custom unitSymbolSeparator.
    • Locale-aware number formatting via locale parameter (using intl package).
    • Full control over number formatting via numberFormat parameter (using intl package).
  • Arithmetic operations (+, -, * by scalar, / by scalar) for most quantities.
  • Specialized arithmetic for Temperature (difference T - T returns double, ratio T / T returns double).
  • Comparable interface implementation for sorting quantities by magnitude.
  • == operator override for value and unit equality.
• Supported Quantity Types (with units and extensions):
  • Length: Meter (m), Kilometer (km), Centimeter (cm), Millimeter (mm), Inch (in), Foot (ft), Yard (yd), Mile (mi), Nautical Mile (nmi).
  • Time: Second (s), Millisecond (ms), Minute (min), Hour (h), Day (d).
  • Temperature: Kelvin (K), Celsius (°C), Fahrenheit (°F). Handles affine conversions correctly.
  • Pressure: Pascal (Pa), Atmosphere (atm), Bar (bar), PSI (psi), Torr, mmHg, inHg, kPa, hPa, mbar, cmH₂O, inH₂O.