## Calculate the inverse of a matrix.

##It is done just once, checking if the result is already in the cache.

## Creates a list containing four functions to set(), get() the matrix

## to getinv() and setinv() to find out it the inverse was

## calculated before

makeCacheMatrix <- function(x = matrix()) {

m <- NULL

set <- function(y) {

x <<- y

m <<- NULL

}

get <- function() x

setinv <- function(mean) m <<- mean

getinv <- function() m

list(set = set, get = get,

setinv = setinv,

getinv = getinv)

}

##Every time the inverse of hte matrix is needed the cache is checked up.

##If the inverse was calculated before it is brought from the cache

##If the inverse wos not calculated, this function does it

cacheSolve <- function(x, ...) {

## Return a matrix that is the inverse of 'x'

m <- x$getinv()

if(!is.null(m)) {

message("getting cached data")

return(m)

}

data <- x$get()

m <- solve(data, ...)

x$setinv(m)

m

}