Assignment solution for peer review

Author: fcappelle

cachematrix.R

@@ -1,15 +1,44 @@
-## Put comments here that give an overall description of what your
-## functions do
+## makeCacheMatrix function creates a matrix wrapper that combines matrix data
+## with its inverse
+## cacheSolve computes the inverse of a matrix created with makeCacheMatrix,
+## if it is called more than once with the same object, the cached value of
+## matrix inverse is returned
+##
+## Example
+## cm <- makeCacheMatrix(matrix(c(1, 0, -4, -2, 2, 5, 1, -8, 9), 3, 3))
+## cacheSolve(cm)
+## second call will return a cached value
+## cacheSolve(cm)
 
-## Write a short comment describing this function
+## returns a matrix wrapper object allowing to cache its inverse
 
 makeCacheMatrix <- function(x = matrix()) {
-
+  xinv <- NULL
+  getinv <- function() xinv
+  setinv <- function(inverse) xinv <<- inverse
+  get <- function() x
+  set <- function(y) {
+    x <<- y
+    xinv <<- NULL
+  }
+  list(get = get, set = set,
+       get.inverse = getinv, set.inverse = setinv)
 }
 
 
-## Write a short comment describing this function
+## Cached version of solve for cache matrix objects,
+## it returns the inverse of x if solve function succeeds
 
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+  ## Return a matrix that is the inverse of 'x'
+  xinv <- x$get.inverse()
+  if (is.null(xinv)) {
+    tryCatch({
+      xinv <- solve(x$get(), ...)
+      x$set.inverse(xinv)
+    }, error = function(e) stop("Non inversible matrix"))
+  } else {
+    message("Getting cached matrix inverse")
+  }
+  xinv
 }