Initial Commit.

Joel M · Joel M · commit e1f23daedc5e · 2016-03-19T13:41:45.000Z
diff --git a/cachematrix.R b/cachematrix.R
@@ -1,15 +1,45 @@
-## Put comments here that give an overall description of what your
-## functions do
-
-## Write a short comment describing this function
+## cachematrix() contains convenience functions for 
+## matrix storage and inversion. The matirx 'x' will have 
+## its inverse calculated once. If the inverse has already 
+## been calculated (and the matrix has not changed), then 
+## the cachesolve() should retrieve the inverse from the cache.
 
+## This function creates a special "matrix" object 
+## that can cache its inverse
 makeCacheMatrix <- function(x = matrix()) {
-
+    im <- NULL
+    
+    set <- function(y){
+        x <- y
+        im <<- NULL
+    }
+   
+    get <- function() x
+    setmatrix <- function(solve) im <<- solve
+    getmatrix <- function() im
+    
+    list( set=set, get=get, 
+          setmatrix=setmatrix,
+          getmatrix=getmatrix)
 }
 
 
-## Write a short comment describing this function
-
+## 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'
+    ## This function assume that the matrix supplied is 
+    ## always invertible.
+    im <- x$getmatrix()
+    if(!is.null(im)){
+        message("getting cached data...")
+        return (im)
+    }
+    m <- x$get()
+    im <- solve(m, ...)
+    x$setmatrix(im)
+    ## Return a matrix that is the inverse of 'x'
+    im
 }
