cachematrix.R

## A pair of functions that cache the inverse of a matrix.
## This function creates a special "matrix" object that can cache its inverse.

makeCacheMatrix <- function(x = matrix()) {  #define the argument, default: "matrix"
    inv <- NULL             ## initialize inv as NULL; will hold value of matrix inverse
    set <- function(y){     ## define the set function to assign new 
        x <<- y             ## value of matrix in parent environment
        inv <<- NULL        #if there is a new matrix, reset inv to NULL
    }                               
    get <- function() x     ## define get function: returns value of the matrix argument
    setInverse <- function(solveMatrix) inv <<- solveMatrix   ### assigns value of inv in parent environment
    getInverse <- function() inv                              ## gets the value of inv where called
    list(set = set, get = get, setInverse = setInverse, getInverse = getInverse)  
    ### you need this in order to refer
    ## to the functions with the $ operator
}


## 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 cacheSolve will retrieve the inverse from the cache

cacheSolve <- function(x, ...) {
    ## Return a matrix that is the inverse of 'x'
    inv <- x$getInverse()
    if(!is.null(inv)){
        message("getting cached data")
        return(inv)
    }
    data <- x$get()
    inv <- solve(data)
    x$setInverse(inv)
    inv
    
    return(inv)
}