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Caching an Inverse of a Matrix Using R

masteramuk profile image Masteramuk ・1 min read

Matrix inversion is usually a costly computation and there may be some benefit to caching the inverse of a matrix rather than computing it repeatedly.

This is an example code to cache an inverse of a matrix which then called if:

  1. The new matrix computation similar to the previous matrix
  2. Matrix is invertible — Read Invertible Matrix
  3. The structure and content of the new matrix is equal to previous The program consists of two functions

A function to cache the matrix and the inverse. It is similar to getter and setter in many programming languages like Java and C.
A function which will be call for the computational process of the matrix

Here are parts of the code:

Setting the matrix

invMatrix <- NULL

#define the set function for the matrix
set <- function(y) {
    x <<- y
    invMatrix <<- NULL
}

Setting the inverse matrix

setInvMatrix <- function(invM){
    invMatrix <<- invM ##assign the inverse matrix to the environment var
} 

##define the function for returning the inverse matrix
getInvMatrix <- function(){
    invMatrix ##the environment var inverse matrix is return
}

Verification on the matrix

if (!is.null(invM)){
    ## check if the return invMatrix is identical
    if ( identical( x$get() %*% invM, invM %*% x$get() ) ){
        ## get it from the cache and skips the computation. 
        print("getting cached data")
        return(invM)
    }
}

Setting the new inverse

data <- x$get()
invM <- solve(data, ...)

# sets the value of the inverse in the cache via the setinv function.
x$setInvMatrix(invM)

Complete source code is reachable at https://github.com/masteramuk/ProgrammingAssignment2

If you like the post, https://www.buymeacoffee.com/masteramuk :)

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