Unit Computation with Pint

Cognitive prosthetics for unit-aware computation. Use Pint for converting between units, performing unit arithmetic, checking dimensional compatibility, and simplifying compound units.

When to Use

• Converting between units (meters to feet, kg to pounds)
• Unit-aware arithmetic (velocity x time = distance)
• Dimensional analysis (is force = mass x acceleration?)
• Simplifying compound units to base or named units
• Parsing and analyzing quantities with units

Quick Reference

| I want to... | Command | Example | |--------------|---------|---------| | Convert units | convert | convert "5 meters" --to feet | | Unit math | calc | calc "10 m/s * 5 s" | | Check dimensions | check | check newton --against "kg * m / s^2" | | Parse quantity | parse | parse "100 km/h" | | Simplify units | simplify | simplify "1 kg*m/s^2" |

Commands

parse

Parse a quantity string into magnitude, units, and dimensionality.

bash
uv run python -m runtime.harness scripts/pint_compute.py \
    parse "100 km/h"

uv run python -m runtime.harness scripts/pint_compute.py \
    parse "9.8 m/s^2"

convert

Convert a quantity to different units.

bash
uv run python -m runtime.harness scripts/pint_compute.py \
    convert "5 meters" --to feet

uv run python -m runtime.harness scripts/pint_compute.py \
    convert "100 km/h" --to mph

uv run python -m runtime.harness scripts/pint_compute.py \
    convert "1 atmosphere" --to pascal

calc

Perform unit-aware arithmetic. Operators must be space-separated.

bash
uv run python -m runtime.harness scripts/pint_compute.py \
    calc "5 m * 3 s"

uv run python -m runtime.harness scripts/pint_compute.py \
    calc "10 m / 2 s"

uv run python -m runtime.harness scripts/pint_compute.py \
    calc "5 meters + 300 cm"

check

Check if two units have compatible dimensions.

bash
uv run python -m runtime.harness scripts/pint_compute.py \
    check newton --against "kg * m / s^2"

uv run python -m runtime.harness scripts/pint_compute.py \
    check joule --against "kg * m^2 / s^2"

simplify

Simplify compound units to base or compact form.

bash
uv run python -m runtime.harness scripts/pint_compute.py \
    simplify "1 kg*m/s^2"

uv run python -m runtime.harness scripts/pint_compute.py \
    simplify "1000 m"

Common Unit Domains

| Domain | Examples | |--------|----------| | Length | meter, foot, inch, mile, km, yard | | Time | second, minute, hour, day, year | | Mass | kg, gram, pound, ounce, ton | | Velocity | m/s, km/h, mph, knot | | Energy | joule, calorie, eV, kWh, BTU | | Force | newton, pound_force, dyne | | Temperature | kelvin, celsius, fahrenheit | | Pressure | pascal, bar, atmosphere, psi | | Power | watt, horsepower |

Output Format

All commands return JSON with relevant fields:

json
{
  "result": "16.4042 foot",
  "magnitude": 16.4042,
  "units": "foot",
  "dimensionality": "[length]",
  "latex": "16.4042\\,\\mathrm{ft}"
}

Error Handling

Dimensionality errors are caught and reported:

bash
# This will error - incompatible dimensions
uv run python -m runtime.harness scripts/pint_compute.py \
    convert "5 meters" --to kg
# Error: Cannot convert '[length]' to '[mass]'

Related Skills

• /math-mode - Full math orchestration (SymPy + Z3)
• /sympy-compute - Symbolic computation