1- # # Put comments here that give an overall description of what your
2- # # functions do
1+ # # makeCacheMatrix and cacheSolve are used to create an object-like list
2+ # # for a square invertible matrix and then solve for the inverse of that matrix.
3+ # # The inverse is cached for later use to speed up program execution.
34
4- # # Write a short comment describing this function
5+ # # The makeCacheMatrix function takes a matrix as input and returns a list of
6+ # # functions to:
7+ # # 1. set the value of the matrix
8+ # # 2. get the value of the matrix
9+ # # 3. set the value of the inverse of the matrix (and cache the value)
10+ # # 4. get the value of the inverse of the matrix
11+ # # Note: The matrix is assumed to be a square invertible matrix.
512
613makeCacheMatrix <- function (x = matrix ()) {
7-
14+ m <- NULL
15+ set <- function (y ) {
16+ x <<- y
17+ m <<- NULL
18+ }
19+ get <- function () x
20+ setinverse <- function (inverse ) m <<- inverse
21+ getinverse <- function () m
22+ list (set = set , get = get ,
23+ setinverse = setinverse ,
24+ getinverse = getinverse )
825}
926
10-
11- # # Write a short comment describing this function
27+ # # The cacheSolve function calculates the inverse of a "makeCacheMatrix" matrix
28+ # # as created above. If this value has already been cached, cacheSolve simply
29+ # # returns the value without having to do any further resource draining calculations.
1230
1331cacheSolve <- function (x , ... ) {
14- # # Return a matrix that is the inverse of 'x'
32+ # # Return a matrix that is the inverse of 'x'
33+ m <- x $ getinverse()
34+ if (! is.null(m )) {
35+ message(" getting cached data"
36+ return (m )
37+ }
38+ data <- x $ get()
39+ m <- solve(data , ... )
40+ x $ setinverse(m )
41+ m
1542}
43+
44+ # # Below is just some example code that can be used to test the above functions.
45+
46+ # test <- matrix(rnorm(9), 3, 3)
47+ # test
48+ # expected <- solve(test)
49+
50+ # cachetest <- makeCacheMatrix(test)
51+ # cachesolvetest <- cacheSolve(cachetest)
52+
53+ # cachesolvetest == expected
54+
55+ # cachesolvetest <- cacheSolve(cachetest)
56+
57+ # # This output shows that the cached value is properly retrieved:
58+ # # > cachesolvetest2 <- cacheSolve(cachetest)
59+ # # getting cached data
60+
61+ # cachesolvetest == cachesolvetest2 & cachesolvetest2 == expected
62+
63+ # # All the calculated inverses are logically equivalent as expected:
64+ # # [,1] [,2] [,3]
65+ # # [1,] TRUE TRUE TRUE
66+ # # [2,] TRUE TRUE TRUE
67+ # # [3,] TRUE TRUE TRUE
0 commit comments