cachematrix.R - making it available on git

cachematrix.R

@@ -1,15 +1,45 @@
-## Put comments here that give an overall description of what your
-## functions do
+library("MASS")
 
-## Write a short comment describing this function
+## These functions are used to calculates the inverse of a matrix
+## stores the result to avoid computations if the result is needed
+## again by some other function to make the function more efficient
 
-makeCacheMatrix <- function(x = matrix()) {
+## The function, `makeCacheMatrix` creates a list containing a function to
+## 1.  set the value of the matrix
+## 2.  get the value of the matrix
+## 3.  set the value of the inverse
+## 4.  get the value of the inverse
 
+makeCacheMatrix <- function(x = matrix()) {
+      inv <- NULL
+      set <- function(y) {
+            x <<- y
+            m <<- NULL
+      }
+      get <- function() x
+      setinv <- function(inverse) inv <<- inverse
+      getinv <- function() inv
+      list(set = set, get = get,
+           setinv = setinv,
+           getinv = getinv)
 }
 
 
-## Write a short comment describing this function
+## Reads a list created by `makeCacheMatrix` function,
+## Checks whether Inverse is calculated or not,
+## If calculated , avoids computation and returns the value 
+## else computes inverse and stores it to avoid recomputing.
+
+## NOTE: Uses `ginv` function in the package MASS for inverse calculation
 
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+      i <- x$getinv()
+      if(!is.null(i)) {
+            message("getting cached data...")
+            return(i)
+      }
+      data <- x$get()
+      i <- ginv(data, ...)
+      x$setinv(i)
+      i
 }