📘 Programming Assignment 2: Lexical Scoping

Overview

This repository contains the completed R code for Programming Assignment 2 in the R Programming course offered by Johns Hopkins University on Coursera.
The objective of this assignment is to demonstrate the use of lexical scoping and closures in R to create a system that caches the inverse of a matrix, improving computational efficiency.

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📂 Contents

• cachematrix.R – Main R script implementing the functions makeCacheMatrix() and cacheSolve().
• README.md – Documentation describing the purpose, functionality, and usage of the code.

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⚙️ Functional Description

makeCacheMatrix(x = matrix())

Creates a special “matrix” object that can store both a matrix and its cached inverse.

Functions returned:

• set(y) – Assigns a new matrix and clears any previously stored inverse.
• get() – Retrieves the current matrix.
• setinv(inv) – Stores the inverse of the matrix in cache.
• getinv() – Retrieves the cached inverse if it exists.

This function demonstrates how closures maintain state between function calls, an important feature of lexical scoping in R.

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cacheSolve(x, ...)

Computes the inverse of the matrix returned by makeCacheMatrix().
If the inverse has already been calculated and the matrix has not changed, it retrieves the cached inverse instead of recomputing it.

Process:

1. Checks if a cached inverse already exists.
2. If yes, retrieves it and prints "Getting cached inverse".
3. If not, computes the inverse using solve(), stores it in cache, and returns it.

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🧮 Example Usage

source("cachematrix.R")

# Create a matrix and its special cached object
m <- matrix(c(2, 1, 1, 2), 2, 2)
cm <- makeCacheMatrix(m)

# Compute the inverse for the first time
cacheSolve(cm)

# Retrieve the cached inverse
cacheSolve(cm)