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37 lines (32 loc) · 1.58 KB
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# These functions owe a lot to the example given in the programming assignment.
# The comments in some cases are tedious, but required for novices.
## This function creates a special "matrix" object that can cache its inverse.
makeCacheMatrix <- function(x = matrix()) {
m <- NULL # m should exist in this context.
set <- function(y) { # a function to set matrix and clear inverse.
x <<- y # assign x and m in their parent contexts.
m <<- NULL
}
get <- function() x # get, a simple function to get the matrix.
setinverse <- function(inverse) m <<- inverse # assign inverse in its parent context.
getinverse <- function() m # getinverse, a simple function to get the inverse.
list(set = set, get = get, # our list of functions
setinverse = setinverse,
getinverse = getinverse)
}
## 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, ...) {
## Return a matrix that is the inverse of 'x'
m <- x$getinverse()
if(!is.null(m)) { # It wasn't null, so its known!
message("getting cached data")
return(m)
}
data <- x$get() # Bring the data into this context
m <- solve(data) # The function that calculates the inverse is solve.
x$setinverse(m) # set the inverse (in a couple contexts up)
m # return the inverse
}