Init Commit For assignment

Init imll for course assignment

Author: hide kojima

cachematrix.R

@@ -1,15 +1,49 @@
-## Put comments here that give an overall description of what your
-## functions do
-
-## Write a short comment describing this function
+## makeCacheMatrix creates a special "vector", 
+# which is really a list containing a function to
+# a) set the value of the matrix
+# b) get the value of the matrix
+# c) set the value of the inverse of the matrix
+# d) get the value of the inverse of the matrix
 
 makeCacheMatrix <- function(x = matrix()) {
-
+  inv <- NULL
+  ## Update existing matrix
+  set <- function(y){
+    x <<- y
+    inv <<- NULL
+  }
+  ## Return original matrix
+  get <- function() x
+  ### Set the inverse of the matrix
+  setinverse <- function(inverse) inv <<- inverse
+  ### Return the inverse of the matrix
+  getinverse <- function() inv
+  list(set = set, get = get,
+       setinverse = setinverse,
+       getinverse = getinverse)
 }
 
-
-## Write a short comment describing this function
+## cacheSolve performs following tasks:
+# 1) check if inverse of the matrix is already created or not
+# 2) return the inverse of the matrix if cached inverse found
+# 3) compute inverse of the matrix if no cache found
+# 4) cache the inverse of the matrix
+# 5) return the inverse of the matrix
 
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+  inv <- x$getinverse()
+  ## check if inverse of the matrix is cached
+  if(!is.null(inv)) {
+    ## return cache if cache is found
+    message("getting cached data")
+    return(inv)
+  }
+  ## if cache is not found, then get the inverse of the matrix.
+  ## first, get the original matrix
+  data <- x$get()
+  ## then get a inverse
+  inv <- solve(data, ...)
+  ### cache retrieved value
+  x$setinverse(inv)
+  inv
 }