ProgrammingAssignment2/cachematrix.R at master · raghuu045/ProgrammingAssignment2 · GitHub

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## These functions are used to create a special object that stores a matrix
## and cache's its inverse.


## makeCacheMatrix function creates a special vector, which is really a list
## containing functions to:
## 1. set the values of the matrix and initialize its cache (set)
## 2. get the values of the matrix (get)
## 3. set the inverse of the matrix (setInv)
## 4. get the inverse of the matrix (getInv)

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


## cacheSolve function calculates the inverse of the special "matrix" created
## with makeCacheMatrix function. However it checks to see if the inverse has
## already been calculated. If so, it gets the inverse from the cache and
## skips the computation. Otherwise it calculates the inverse of the matrix
## and sets the value of the inverse in the cache via the setInv function.

cacheSolve <- function(x, ...) {
        inv <- x$getInv()
        if(!is.null(inv)) {
                message("getting cached inverse")
                return(inv)
        }
        mat <- x$get()
        inv <- solve(mat, ...)
        x$setInv(inv)
        inv
}

## Usage: Example


## Matrix supplied should be invertible
## > x <- c(8,9,10,11)
## > mat1 <- matrix(x,2,2)
## > a <- makeCacheMatrix(mat1)
## > a$get()
##     [,1] [,2]
##     [1,]    8   10
##     [2,]    9   11
## > a$getInv()
## NULL
## > cacheSolve(a)
##     [,1] [,2]
## [1,] -5.5    5
## [2,]  4.5   -4
## > cacheSolve(a)
## getting cached inverse
##      [,1] [,2]
## [1,] -5.5    5
## [2,]  4.5   -4
## > a$getInv()
##      [,1] [,2]
## [1,] -5.5    5
## [2,]  4.5   -4
## > a$get()
##      [,1] [,2]
## [1,]    8   10
## [2,]    9   11


## Supplying a new invertible matrix
## > y <- c(12,13,14,15)
## > mat2 <- matrix(y,2,2)
## > a$set(mat2)
## > a$get()
##      [,1] [,2]
## [1,]   12   14
## [2,]   13   15
## > cacheSolve(a)
##      [,1] [,2]
## [1,] -7.5    7
## [2,]  6.5   -6
## > cacheSolve(a)
## getting cached inverse
##      [,1] [,2]
## [1,] -7.5    7
## [2,]  6.5   -6
## > a$getInv()
##      [,1] [,2]
## [1,] -7.5    7
## [2,]  6.5   -6
## > a$get()
##      [,1] [,2]
## [1,]   12   14
## [2,]   13   15