commit rdpeng#1

swsan · swsan · commit 95a949dab528 · 2022-11-10T01:06:23.000+08:00
diff --git a/.gitignore b/.gitignore
@@ -0,0 +1,4 @@
+.Rproj.user
+.Rhistory
+.RData
+.Ruserdata
diff --git a/ProgrammingAssignment2.Rproj b/ProgrammingAssignment2.Rproj
@@ -0,0 +1,13 @@
+Version: 1.0
+
+RestoreWorkspace: Default
+SaveWorkspace: Default
+AlwaysSaveHistory: Default
+
+EnableCodeIndexing: Yes
+UseSpacesForTab: Yes
+NumSpacesForTab: 2
+Encoding: UTF-8
+
+RnwWeave: Sweave
+LaTeX: pdfLaTeX
diff --git a/cachematrix.R b/cachematrix.R
@@ -2,14 +2,48 @@
 ## functions do
 
 ## Write a short comment describing this function
-
+## makeCacheMatrix will return a list containing 4 functions, set(), get(), setinverse() and getinverse()
+## in function space, it holds matrix x and inverse inv_x
 makeCacheMatrix <- function(x = matrix()) {
-
+  inv_x <- NULL
+  set <- function(y) {
+    x <<- y
+  }
+  get <- function() x
+  setinverse <- function(y) inv_x <<- y
+  getinverse <- function() inv_x
+  list(set = set, get = get,
+       setinverse = setinverse,
+       getinverse = getinverse)
 }
 
 
 ## Write a short comment describing this function
-
+## cacheSolve will return the inverse matrix inv_x and alse set the inv_x held in makeCacheMatrix
 cacheSolve <- function(x, ...) {
-        ## Return a matrix that is the inverse of 'x'
+  ## Return a matrix that is the inverse of 'x'
+  inv_m <- x$getinverse()
+  if(!is.null(inv_m)) {
+    message("getting cached data")
+    return(inv_m)
+  }
+  
+  m <- x$get()
+  inv_m <- solve(m)
+  x$setinverse(inv_m)
+  inv_m 
 }
+
+###testing 
+a <- matrix(c(1,3,2,5,4,3,3,4,5),nrow=3,ncol=3)
+x <- makeCacheMatrix(a)
+x$get()
+x$getinverse()
+cacheSolve(x)
+b1 <- x$get()
+b2 <- x$getinverse()
+b1
+b2
+b1 %*% b2
+b2 %*% b1
+
