wolpha-calculator

A simple Wolfram Alpha alternative

(Trigger warning: Jank implementation)

Usage

To use it, submit POST requests to the endpoint with the body as an expression you want to calculate.

Example: curl -d "420+69" -H "Content-Type: text/plain" -X POST https://wolpha-calculator.herokuapp.com/ would return 489.0.

Features

1. Arbitrary input precision, up to 10 decimal digits of output precision.
2. Elementary operations: +, -, * or x, /, ^
3. Elementary functions: sin, cos, tan, sqrt, ln or log
4. Parenthesis and order of operations (PEMDAS)
5. Constants: e and pi
6. Decimals and negative values (e.g., -1.5)

Example

1. 1+1 returns 2.0
2. 5-(-1.9) returns 6.9
3. 2+2*2 returns 6.0 (by PEMDAS)
4. 2^2^3 returns 256.0 (evaluate right to left for exponents)
5. sin(cos(pi/2)) returns 0.0
6. 1.99999999999999999999 returns 2.0
7. error returns HTTP 400

Setup

(The rest of this file is only for if you want to host the repository separately.)

Local Setup

1. Clone this repository.
2. Install and initialize PostgreSQL.
3. Run the program with specified environment variables.

Environment Variables

1. DB_HOST: Host name (e.g., localhost)
2. DB_PORT: PostgreSQL port (e.g., 5432)
3. DB_USER: Username (e.g., jean)
4. DB_PASS: Password (e.g., password)
5. DB_NAME: Database (e.g., jean)

Heroku Setup

1. Create a Heroku app, then push the repository.
2. View database credentials at App -> Resources -> Heroku Postgres -> Settings -> View Credentials...
3. To access the database, use heroku pg:psql.
4. View the table using SELECT * FROM entity.