cachematrix.R

## To avoid repetitive costly computations, these functions will 
## cache the inverse of a matrix so that it only needs to be computed
## once and stored for future use.

## From assignment description: This function creates a special 
## "matrix" object that can cache its inverse.

makeCacheMatrix <- function(x = matrix()) {
    inv <- NULL
    set <- function(y) {
        x <<- y
        inv <- NULL
    }
    get <- function() x 
    setinv <- function(inverse) inv <<- inverse
    getinv <- function() inv
    list(set = set, get = get, setinv = setinv, getinv = getinv)
}


## From assignment description: 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 the cachesolve should retrieve the inverse from 
## the cache.

cacheSolve <- function(x, ...) {
    inv <- x$getinv()
    if(!is.null(inv)) {
        message('getting cached data')
        return(inv)
    }   
    data <- x$get()
    inv <- solve(data, ...)
    x$setinv(inv)
    inv 
}