cpc

calculation + conversion

cpc calculates complex strings of math, with support for units and conversion. 128-bit decimal floating points are used for high accuracy.

For example 1tonne * 1sqm / 2second^3 / 5ampere results in 100 volts.

List of all supported units

Web Interface

Try it out at cpc.kasper.space

CLI Installation

Install using cargo:

cargo install cpc

To install it manually, grab the appropriate binary from the GitHub Releases page and place it wherever you normally place binaries on your OS.

CLI Usage

cpc '2h/3 to min'

CLI REPL Usage

cpc
> sin(1)
≈ 0.84147098480789650665250232163029899962

Examples

3 + 4 * 2
6'3" to cm
1tonne * 1sqm / 2s^3 / 5a
(7 % 4)km to light years
10m/2s * 5 trillion s
1 lightyear * 0.001mm in km2
1m/s + 1mi/5h in kilometers per h
round(sqrt(2)^4)! liters
10% of abs(sin(pi)) horsepower to watts

Supported unit types

• Normal numbers
• Area
• Currency
• Digital storage (bytes etc)
• Electric current
• Energy
• FLOPS
• Frequency
• Length
• Mass
• Power
• Pressure
• Resistance
• Speed
• Temperature
• Time
• Voltage
• Volume

API Installation

Add cpc as a dependency in Cargo.toml.

API Usage

use cpc::eval;use cpc::units::Unit;matcheval("3m + 1cm",true,false){Ok(answer) => {// answer: Number { value: 301, unit: Unit::Centimeter }println!("Evaluated value: {} {:?}", answer.value, answer.unit)},Err(e) => {println!("{e}")}}

Accuracy

Inexact results are always indicated with ≈. 128-bit Decimal Floating Point (d128) numbers are used for high accuracy, and prevents most floating-point errors.

Dev Instructions

Get started

Install Rust.

Run cpc with a CLI argument as input:

cargo run -- '100ms to s'

Run in verbose mode, which shows some extra logs:

cargo run -- '100ms to s' --verbose

Run tests:

cargo test

Build:

cargo build

Adding a unit

Nice resources for adding units:

• https://wolframalpha.com
• https://github.com/ryantenney/gnu-units/blob/master/units.dat
• https://support.google.com/websearch/answer/3284611 (unit list)
• https://translatorscafe.com/unit-converter (unit conversion)
• https://calculateme.com (unit conversion)
• https://wikipedia.org

1. Add the unit

In src/units.rs, units are specified like this:

pubenumUnitType{Time,// etc}// ...create_units!(Nanosecond:(Time, d!(1),"nanosecond","nanoseconds"),Microsecond:(Time, d!(1000),"microsecond","microseconds"),// etc)

The number associated with a unit is it's "weight". For example, if a second's weight is 1, then a minute's weight is 60.

2. Add a test for the unit

Make sure to also add a test for each unit. The tests look like this:

assert_eq!(convert_test(1000.0,Meter,Kilometer),1.0);

Basically, 1000 Meter == 1 Kilometer.

3. Add the unit to the lexer

Text is turned into tokens (some of which are units) in lexer.rs. Here's one example:

// ...match string {"h" | "hr" | "hrs" | "hour" | "hours" => tokens.push(Token::Unit(Hour)),// etc}// ...

Potential Improvements

• Fractional numbers (to make 1/3*2*3 accurate)
• E notation, like 2E+10
• Unit types
  • Timezones
  • Binary/octal/decimal/hexadecimal/base32/base64
  • Color codes
  • Roman numerals

Releasing a new version

1. Update CHANGELOG.md
2. Bump the version number in Cargo.toml
3. Run cargo test
4. Create a git tag in format v#.#.#
5. Add release notes to the generated GitHub release and publish it
6. Run cargo publish