Parallel Example in RStudio as run via knitr after being written in R markdown…

library(foreach)
library(parallel)
library(doParallel)

## Loading required package: iterators

demo(sincParallel)

## 
## 
##  demo(sincParallel)
##  ---- ~~~~~~~~~~~~
## 
## > library(doParallel)
## 
## > registerDoParallel()
## 
## > # Define a function that creates an iterator that returns subvectors
## > ivector <- function(x, chunks) {
## +   n <- length(x)
## +   i <- 1
## + 
## +   nextEl <- function() {
## +     if (chunks <= 0 || n <= 0) stop('StopIteration')
## +     m <- ceiling(n / chunks)
## +     r <- seq(i, length=m)
## +     i <<- i + m
## +     n <<- n - m
## +     chunks <<- chunks - 1
## +     x[r]
## +   }
## + 
## +   obj <- list(nextElem=nextEl)
## +   class(obj) <- c('abstractiter', 'iter')
## +   obj
## + }
## 
## > # Define the coordinate grid and figure out how to split up the work
## > x <- seq(-10, 10, by=0.1)
## 
## > nw <- getDoParWorkers()
## 
## > cat(sprintf('Running with %d worker(s)\n', nw))
## Running with 3 worker(s)
## 
## > # Compute the value of the sinc function at each point in the grid
## > z <- foreach(y=ivector(x, nw), .combine=cbind) %dopar% {
## +   y <- rep(y, each=length(x))
## +   r <- sqrt(x ^ 2 + y ^ 2)
## +   matrix(10 * sin(r) / r, length(x))
## + }
## 
## > # Plot the results as a perspective plot
## > persp(x, x, z, ylab='y', theta=30, phi=30, expand=0.5, col="lightblue")