# Getting Started Install Epsil and run your first symbolic program in five minutes. :::warning[Experimental] Epsil is experimental. Its syntax and behavior may change between releases. ::: ## Install Epsil is included with the Compute Engine package: ```shell npm install @cortex-js/compute-engine ``` The package installs an `epsil` command. During development, run the project-local command through `npx`. ## Try the REPL Start an interactive session: ```shell npx epsil ``` Enter a declaration, then use it in another expression: ```text epsil> let x = 5 5 epsil> x^2 25 ``` The REPL keeps declarations and assignments between inputs. Enter `.help` for the available commands and `.exit` when you are done. ## Run a Source File Save this program as `squares.epsil`: ```epsil square(x) = x^2 Map(1..5, square) ``` Run it: ```shell npx epsil squares.epsil ``` The result is: ```text [1,4,9,16,25] ``` The conventional file extension is `.epsil`. ## Work Symbolically Epsil uses the Compute Engine, so expressions remain exact and symbolic by default: ```epsil-live Simplify(2 + 3x^3 + 2x^2 + x^3 + 1) ``` Use `N()` when you want a numeric approximation: ```epsil-live N(Sqrt(2)) ``` ## Embed Epsil in JavaScript Import the experimental Epsil entry point, create a `ComputeEngine`, then execute source text: ```js import { ComputeEngine, executeEpsil, } from "@cortex-js/compute-engine/epsil"; const ce = new ComputeEngine(); const { value, diagnostics } = executeEpsil( ce, "factorial(n) = 1 if n <= 1 else n * factorial(n - 1)\nfactorial(10)" ); if (diagnostics.length > 0) console.error(diagnostics); console.log(value.toString()); // 3628800 ``` Calls made with the same `ComputeEngine` share its top-level declarations, which is useful for notebook cells and other stateful sessions. Create a fresh engine when you want an isolated program. ## Where to Go Next Study **complete programs** covering control flow, collections, symbolic calculus, linear algebra, strings, and reproducible randomness. Learn the **CLI and REPL** commands, output modes, diagnostics, and evaluation limits. Use the **language reference** for syntax, operators, declarations, types, and control flow. Already know **Python**? Start from the idiom-by-idiom translation guide. Already know **Mathematica**? Start from the Wolfram Language translation guide.