cachematrix.R

## Caching the inverse of a matrix using the <<- operator to assign a value to an object in a different environment.
## A special object stores the matrix and it's inverse.
##
## To test ths code
## 1. Check inverse of identity matrix, should return TRUE
## m=makeCacheMatrix(matrix(c(1,0,0,0,1,0,0,0,1),nrow=3,ncol=3))
## n=makeCacheMatrix(cacheSolve(m))
## all.equal(m$get(),n$get())
##
## 2. Test that inverse of inverse are equal, both should return TRUE
## m=makeCacheMatrix(matrix(c(1,2,3,4,6,8,5,8,12),nrow=3,ncol=3))
## n=makeCacheMatrix(cacheSolve(m))
## all.equal(cacheSolve(n),m$get())
## all.equal(cacheSolve(m),n$get())

## makeCacheMatrix creates a special "matrix" object that is really a list of functions to
## 1. set the value of the matrix
## 2. get the value of the matrix
## 3. set the value of the inverse
## 4. get the value of the inverse
makeCacheMatrix <- function(x = matrix()) {
  s <- NULL
  set <- function(y) {
    x <<- y
    s <<- NULL
  }
  get <- function() x
  setsolve <- function(solve) s <<- solve
  getsolve <- function() s
  list(set = set, get = get,
       setsolve = setsolve,
       getsolve = getsolve)
}


## cacheSolve calculates the inverse of the special matrix created with makeCacheMatrix.
## It first checks to see if the inverse has already been solved using the getsolve function.
## If so, it returns the inverse from the cache and skips the computation. Otherwise, it
## solves the inverse of the matrix and sets the value in the cache via the setsolve function.
cacheSolve <- function(x, ...) {
  s <- x$getsolve()
  if(!is.null(s)) {
    message("getting cached data")
    return(s)
  }
  data <- x$get()
  s <- solve(data, ...)
  x$setsolve(s)
  s
}