cachematrix.R

# Functions for caching the inverse of a matrix with it.

makeCacheMatrix <- function(x = matrix()) {
  # Create a Matrix object (an R list in fact) that encapsulates a matrix
  # and provides methods to set() and get() the orginal matrix and
  # to setInverse() and getInverse() its inverse, to cache it.
  #
  # Args:
  #   x: The matrix to encapsulate.
  #
  # Returns:
  #   The cached matrix object.
  
  # The cached inverse of the matrix.
  inverseOfMatrix <- NULL
  
  set <- function(original) {
    # Set, i.e. preserve, the original matrix;
    # and clear its, perhaps previously cached, inverse.
    #
    # Args:
    #   original: The original matrix to be preserved.
    #
    # Retuns:
    #   NULL
    
    x <<- original
    inverseOfMatrix <<- NULL
  }
  
  get <- function() {
    # Get the orginal matrix.
    #
    # Args:
    #
    # Retuns:
    #   The original matrix.
    
    x
  }
  
  setInverse <- function(inverse) {
    # Set, i.e. preserve, the inverse of the matrix.
    #
    # Args:
    #   inverse: The inverse of the matrix to be cached.
    #
    # Retuns:
    #   The inverse.
    
    inverseOfMatrix <<- inverse
  }
  
  getInverse <- function() {
    # Get the inverse of the matrix
    #
    # Args:
    #
    # Retuns:
    #   The inverse.
    
    inverseOfMatrix
  }
  
  list(set = set, get = get, setInverse = setInverse, getInverse = getInverse)
}


cacheSolve <- function(x, ...) {
  # Compute the inverse of the special "matrix" returned by makeCacheMatrix above.
  # If the inverse has already been calculated (and the matrix has not changed),
  # then get the inverse from the cache.
  #
  # Args:
  #   x: The matrix to invert and cache.
  #   ...: additional argumenst are passed to solve()
  #
  # Returns:
  #   The, perhaps previously cached, inverse.

  inverse <- x$getInverse()
  if (is.null(inverse)) {
    message("Patience, calculating inverse ...")
    
    original <- x$get()
    inverse <- solve(original, ...)
    x$setInverse(inverse)
  }
  
  inverse
}

## Test
# m <- matrix(data = c(0, 1, 1, 0), nrow = 2, ncol = 2)
# mc <- makeCacheMatrix(m)
# cacheSolve(mc)
## Patience, calculating inverse ...
## ... inverse matrix
# cacheSolve(mc)
## ... inverse matrix
# identical(mc$get(), mc$getInverse())
## [1] TRUE