tsurudak
diff --git a/‎cachematrix.R
Lines changed: 48 additions & 6 deletions b/‎cachematrix.R
Lines changed: 48 additions & 6 deletions
@@ -1,15 +1,57 @@
-## Put comments here that give an overall description of what your
-## functions do
+##############################################################################
+##
+## KT
+## Programming assignment 2
+## R Programming Course (Coursera, April 2014)
+##
+## Contains a function that creates a special "matrix" that can cache its inverse
+## And a second function that calculates or retrieves (depending on whether it
+## exists already) the inverse of said "special matrix and returns that inverse
+##
+##############################################################################
 
-## Write a short comment describing this function
 
-makeCacheMatrix <- function(x = matrix()) {
 
+## makeCacheMatrix creates a list that contains functions to:
+##      1. set the value of a matrix
+##      2. get the value of a matrix
+##      3. set the value of an invserse of a matrix
+##      4. get the value of an invserse of a matrix
+
+makeCacheMatrix <- function(x = matrix()) {
+        m <- NULL
+        set <- function(y) {
+                x <<- y #set matrix equal to matrix value
+                m <<- NULL #set inverse to NULL
+        }
+        get <- function() x ## return matrix
+        setinverse <- function(inverse) m <<- inverse #set inverse of matrix
+        getinverse <- function() m #return the inverse of matrix
+        
+        #return list with functions 1-4 as listed above in large comment
+        list(set = set, 
+             get = get, 
+             setinverse = setinverse,  
+             getinverse = getinverse)
 }
 
 
-## Write a short comment describing this function
+
+
+## cacheSolve returns the inverse of an invertable matrix.
+## First, it checks if the inverse of the matrix has already been calculated
+## If so, it "gets" this inverse and returns it. Otherwise, it calculates the 
+## inverse, sets the value of the inverted matrix using the 'setinverse' 
+## function, and returns the inverse
 
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+        m <- x$getinverse() #check if matrix inverse has already been calculated
+        if(!is.null(m)) { # if inverse is already calculated
+                message("fetching cached data")
+                return(m) # return inverse and exit function
+        }
+        data <- x$get() # if matrix inverse hasn't been calculated, get matrix
+        m <- solve(data, ...) # solve the inverse
+        x$setinverse(m) # set the inverse
+        m # return the inverse and exit function
 }