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https://github.com/mds1/solidity-trigonometry
Solidity library with basic trigonometry functions
https://github.com/mds1/solidity-trigonometry
Last synced: about 2 months ago
JSON representation
Solidity library with basic trigonometry functions
- Host: GitHub
- URL: https://github.com/mds1/solidity-trigonometry
- Owner: mds1
- License: mit
- Created: 2021-10-31T22:33:53.000Z (about 3 years ago)
- Default Branch: main
- Last Pushed: 2023-03-09T04:22:15.000Z (almost 2 years ago)
- Last Synced: 2024-10-14T06:27:20.754Z (2 months ago)
- Language: Solidity
- Size: 83 KB
- Stars: 145
- Watchers: 2
- Forks: 18
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Solidity Trigonometry
Solidity library offering basic trigonometry functions where inputs and outputs are integers.
Inputs are specified in radians scaled by 1e18, and similarly outputs are scaled by 1e18.
Each invocation of the `sin()` and `cos()` functions cost around 1600–1700 gas (see the `testNoReverts` costs in `.gas-snapshot` for more info).
This implementation is based off the Solidity trigonometry library written by
[Lefteris Karapetsas](https://twitter.com/LefterisJP)
which can be found [here](https://github.com/Sikorkaio/sikorka/blob/e75c91925c914beaedf4841c0336a806f2b5f66d/contracts/trigonometry.sol).
Compared to Lefteris' implementation, this version makes the following changes:
- Uses a 32 bits instead of 16 bits for improved accuracy
- Updated for Solidity 0.8.x
- Various gas optimizations
- Change inputs/outputs to standard trig format (scaled by 1e18) instead of requiring the integer format used by the algorithm
The original implementation by Lefteris is based off Dave Dribin's [trigint](http://www.dribin.org/dave/trigint/) C library,
which in turn is based on an [article](http://web.archive.org/web/20120301144605/http://www.dattalo.com/technical/software/pic/picsine.html) by Scott Dattalo.
## Usage
When using this library, it's recommended to wrap input values (which are in radians) between `2 * PI * 1e18` and `4 * PI * 1e18` to avoid precision errors.
This is equivalent to wrapping standard values between 0 and 2π. There is some flexibility on that range, but it should stay within reasonable bounds.
To use this in a [Foundry](https://github.com/gakonst/foundry/) project, install it with:
```sh
forge install https://github.com/mds1/solidity-trigonometry
```
To use this in a [dapptools](https://github.com/dapphub/dapptools/) project, install it with:
```sh
dapp install https://github.com/mds1/solidity-trigonometry
```
There is currently no npm package, so for projects using npm for package management, such as [Hardhat](https://hardhat.org/) projects, use:
```sh
yarn add https://github.com/mds1/solidity-trigonometry.git
```
## Development
### Setup
This library is developed with [Foundry](https://github.com/dapphub/dapptools/).
If you don't have Foundry installed, run the command below to get `foundryup`, the Foundry toolchain installer:
```
curl -L https://foundry.paradigm.xyz | bash
```
Then in a new terminal session or after reloading your PATH, run `foundryup` to get the latest `forge` and `cast` binaries.
### Testing
Run tests with `forge test`, and update gas snapshots with `FOUNDRY_FUZZ_RUNS=50000 forge snapshot` (this will take a while to run since that many FFI runs can be slow).
NOTE: Tests are configured to run with the `--ffi` flag enabled for fuzz testing, so review the test commands before executing them to ensure you aren't running any malicious code on your machine.