# RPN Virtual Calculator

A browser-friendly RPN calculator built around a small, generic JavaScript API.

## Goal

This project defines a reusable RPN calculator engine with:

- a simple stack-based public API
- configurable numeric and UI behavior
- centralized command metadata
- a browser demo that uses the same public API as any consumer code

# RPN Virtual Calculator

A browser-friendly RPN calculator built around a small, generic JavaScript API.

## Goal

This project provides a reusable Reverse Polish Notation (RPN) calculator engine with:

- a simple stack-based public API
- configurable numeric behavior
- centralized command metadata
- browser demos that use the same public API as any consumer code

## Project structure

- `src/rpn-calculator.js`: calculator engine
- `samples/dev/index.html`: browser demo
- `samples/hp48/index.html`: HP48-style browser demo

## Main features

- Single JavaScript class: `RpnCalculator`
- Configurable stack size via `maxSize` (default: `2048`)
- Configurable numeric base via `base` (default: `10`)
- Configurable angle mode via `angleMode`:
  - `deg` (default)
  - `rad`
  - `grad`
- Optional command filtering through `enabledCommands`
- Public API limited to generic methods:
  - `push(value)`
  - `pop()`
  - `clear()`
  - `swap(index1, index2)`
  - `remove(index)`
  - `edit(index)`
  - `isValidIndex(index)`
  - `input(command)`
  - `command(name, ...args)`
- `inputValue` is always stored as a string
- `isEditing` is exposed as a boolean
- Supported operations are centralized in one dictionary with metadata such as:
  - `argCount`
  - `category`
  - `aliases`
- Supported categories are limited to:
  - `Stack`
  - `Arithmetic`
  - `Trigonometry`
## Available constants

- `pi`
- `e`

## Supported commands

### Arithmetic
- `add` (`+`)
- `sub` (`-`)
- `mul` (`*`)
- `div` (`/`)
- `mod` (`%`)
- `pow` (`^`, `y^x`)
- `sqr`
- `neg`
- `sqrt`
- `recip` (`1/x`)
- `log`
- `ln`

### Trigonometry
- `sin`
- `cos`
- `tan`
- `asin`
- `acos`
- `atan`

### Stack
- `dup`
- `drop`
- `swap`
- `clear`
- `enter`

## Behavior rules

- `mod` is a percentage operator:
  - `a b % => (a * b) / 100`
- `log` uses `Math.log10`
- `ln` uses `Math.log`
- `sqrt`, `asin`, `acos`, `log`, and `ln` throw explicit domain errors on invalid input
- Trigonometric behavior depends on `angleMode`
- In degree mode:
  - `sin`, `cos`, `tan` convert degrees to radians internally
  - `asin`, `acos`, `atan` return degrees
- `inputValue` remains a string to preserve future support for formats such as hexadecimal input

## Basic usage

### In a browser
- `rpn-calculator.js`: calculator engine
- `rpn-example.html`: example browser interface

## Main features
- Single JavaScript class
- Configurable stack size (`maxSize`, default: `2048`)
- Configurable numeric base (`base`, default: `10`)
- Configurable angle mode (`angleMode`, default: `deg`)
- Optional command filtering through `enabledCommands`
- Generic public API centered on:
  - `push`
  - `pop`
- `clear`
  - `swap(index1, index2)`
  - `remove(index)`
  - `edit(index)`
  - `isValidIndex(index)`
  - `input(command)`
  - `command(name, ...args)`
- `inputValue` is kept as a string to preserve future input formats
- `isEditing` is exposed as a boolean state
- All supported commands are described in one centralized dictionary
- Supported categories are limited to:
  - `Stack`
  - `Arithmetic`
  - `Trigonometry`

## Basic usage

### In a browser