numero

numero is software for parsing and evaluating mathematical expressions. It is available as a library and as a web service.

usage

The library can be used as follows.

Download it:

go get -u github.com/viveknathani/numero

Import it:

import "github.com/viveknathani/numero/nparser"

Simple example:

expression := "sin(max(2, 3333))"
parser := nparser.New(expression)

result, err := parser.Run()

Example with variables:

expression := "x + y"
parser := New(expression)
parser.SetVariable("x", 2)
parser.SetVariable("y", 45)
result, err := parser.Run()

The web service can be consumed as follows:

curl --request POST \
  --url https://${your_self_hosted_url}/api/v1/eval \
  --header "Content-Type: application/json" \
  --data '{"expression":"x + sin(max(2, 333))","variables":{"x":100}}'

documentation

Supported functions

• sin
• cos
• tan
• log
• ln
• sqrt
• max
• min

Supported operators

• +
• -
• *
• /
• ^

API

POST /api/v1/eval

Request body parameters (JSON):

• expression: the expression to evaluate
• variables: a map of variable names to values

Response body:

{
  "data": {
    "result": 99.99117883388611
  },
  "message": "success"
}

benchmarks

This runs a load test for 20 seconds. The test can be found here. The tests were run on a 2021 Macbook Pro with an M1 chip.

make bench

metric	value
total requests	30878
successful requests	30878
failed requests	688
connection errors	688
invalid responses	0
average latency	1.02 ms
min latency	0.06 ms
max latency	36.12 ms
requests/second	1543

contributing

I am happy to accept pull requests. No hard rules.

To set up the project for development, we have the following system requirements:

1. git
2. go
3. make

git clone https://github.com/viveknathani/numero.git
cd numero
make build
make test
make run-dev

motivation

This project started as an exercise in doing some recreational programming. I always knew about the shunting yard algorithm but never really got to implement it. Lately, I've been writing a lot of code in Go and decided to just do this.

acknowledgements

created by Vivek Nathani (@viveknathani_), licensed under the MIT License.