Implement the functions makeCacheMatrix and cacheSolve

Author: JonathanS

cachematrix.R

@@ -1,15 +1,47 @@
-## Put comments here that give an overall description of what your
-## functions do
+# Coursera - R Programming - Programming Assignment 2
+# Caching the Inverse of a Matrix
 
-## Write a short comment describing this function
+# makeCacheMatrix: This function creates a special "matrix" object that can 
+# cache its inverse
 
 makeCacheMatrix <- function(x = matrix()) {
-
+    m <- NULL
+    set <- function(y) {
+        x <<- y
+        m <<- NULL
+    }
+    get <- function() x
+    setsolve <- function(solve) m <<- solve
+    getsolve <- function() m
+    list(set = set, get = get,
+         setsolve = setsolve,
+         getsolve = getsolve)
 }
 
-
-## Write a short comment describing this function
+# cacheSolve: This function computes the inverse of the special "matrix" 
+# returned by makeCacheMatrix above. If the inverse has already been 
+# calculated (and the matrix has not changed), then the cachesolve should 
+# retrieve the inverse from the cache.
 
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+    ## Return a matrix that is the inverse of 'x'
+    m <- x$getsolve()
+    if(!is.null(m)) {
+        message("getting cached data")
+        return(m)
+    }
+    data <- x$get()
+    m <- solve(data, ...)
+    x$setsolve(m)
+    m
 }
+
+# Tested as follows:
+# m1 <- matrix(c(1,2,3,4), nrow = 2, ncol = 2)
+# m2 <- matrix(c(10, 9, 8, 7), nrow = 2, ncol = 2)
+# cm <- makeCacheMatrix(m1)
+# cacheSolve(cm) # doesn't use cache, returns solve(m1)
+# cacheSolve(cm) # returns cached result
+# cm$set(m2)
+# cacheSolve(cm) # doesn't use cache, returns solve(m2)
+# cacheSolve(cm) # returns cached result