rdpeng · Nov 23, 2014
Showing with 32 additions and 8 deletions.

+32 −8 cachematrix.R
diff --git a/cachematrix.R b/cachematrix.R
@@ -1,15 +1,39 @@
-## Put comments here that give an overall description of what your
-## functions do
-
-## Write a short comment describing this function
+# Matrix inversion is usually a costly computation and there may be some benefit
+# to caching the inverse of a matrix rather than compute it repeatedly. The
+# following two functions are used to cache the inverse of a matrix.
 
+# makeCacheMatrix creates a list containing a function to
+# 1. set the value of the matrix
+# 2. get the value of the matrix
+# 3. set the value of inverse of the matrix
+# 4. get the value of inverse of the matrix
 makeCacheMatrix <- function(x = matrix()) {
-
+    inv <- NULL
+    set <- function(y) {
+        x <<- y
+        inv <<- NULL
+    }
+    get <- function() x
+    setinverse <- function(inverse) inv <<- inverse
+    getinverse <- function() inv
+    list(set=set, get=get, setinverse=setinverse, getinverse=getinverse)
 }
 
 
-## Write a short comment describing this function
+# The following function returns the inverse of the matrix. It first checks if
+# the inverse has already been computed. If so, it gets the result and skips the
+# computation. If not, it computes the inverse, sets the value in the cache via
+# setinverse function.
 
+# This function assumes that the matrix is always invertible.
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
-}
+    inv <- x$getinverse()
+    if(!is.null(inv)) {
+        message("getting cached data.")
+        return(inv)
+    }
+    data <- x$get()
+    inv <- solve(data)
+    x$setinverse(inv)
+    inv
+}