Update cache matrix code, add test found at

juliakm · juliakm · commit 5d2725eded81 · 2015-02-15T14:11:31.000-05:00
http://masterr.org/r/how-to-cache-a-matrix-inversion-in-r/
diff --git a/cachematrix.R b/cachematrix.R
@@ -1,29 +1,20 @@
-## Put comments here that give an overall description of what your
-## functions do
-
-## This function creates a special "matrix" object
-## that can cache its inverse.
+## This function creates a special "matrix" object that can cache its inverse.
 
 makeCacheMatrix <- function(x = matrix()) {
     matrix <- NULL
-    set <- function(y) {
+    set <- function(y) { #set is a function to set the value of inverse
         x <<- y ## search through parent environment first for a value for y and assign to x
         inverse <<- NULL ## set the inverse to null, unless it already exists
     }
-    get <- function() x
+    get <- function() x #get is a function to get the value of the matrix
     setinverse <- function(inverse) x <<- inverse #set the inverse value
     getinverse <- function() x #get the inverse value
-    list(set = set, get = get,
+    list(set = set, get = get, #create a list with the values of each function
          setinverse = setinverse,
          getinverse = getinverse)
-    }
 }
 
-## This function computes the inverse of the special
-## "matrix" returned by `makeCacheMatrix` above. 
-## Computing the inverse of a square matrix can be done with the `solve`
-## function in R.
-## n is the inverted matrix
+## cacheSolve calculates the inverse of the “matrix” returned by makeCacheMatrix()
 cacheSolve <- function(x, ...) {
         ## Return a matrix that is the inverse of 'x'
     n <- x$getinverse()
@@ -32,7 +23,7 @@ cacheSolve <- function(x, ...) {
         return(n) #return the cached inverted matrix if it already exists
     }
     data <- x$get() #if we don't have a in existing inverted matrix, create one
-    n <- solve(data, ...)
+    n <- solve(data, ...) #use solve() to find the inverse
     x$setinverse(n)
-    n
+    n #resturn the inverse
 }
diff --git a/test_assignment2.R b/test_assignment2.R
@@ -0,0 +1,15 @@
+test = function(mat){
+    ## @mat: an invertible matrix
+    
+    temp = makeCacheMatrix(mat)
+    
+    start.time = Sys.time()
+    cacheSolve(temp)
+    dur = Sys.time() - start.time
+    print(dur)
+    
+    start.time = Sys.time()
+    cacheSolve(temp)
+    dur = Sys.time() - start.time
+    print(dur)
+}
