The knitr package (Xie 2016) is an alternative tool to Sweave based on a different design with more features. This document is not an introduction, but only serves as a placeholder to guide you to the real manuals, which are available on the package website https://yihui.org/knitr/1, and remember to read the help pages of functions in this package. There is a book (Xie 2015) for this package, but it may not be useful to those who prefer digging out information on the web.
Anyway, here is a code chunk that shows you can compile vignettes with knitr as well using R 3.0.x, which supports non-Sweave vignettes:
options(digits = 4) rnorm(20)
##  -0.23874 0.64966 0.33609 -1.47118 0.03510 1.10477 -0.20795 1.99558 ##  -0.72976 -0.68573 -0.83419 -0.01535 -0.52255 0.38385 0.34621 -0.46441 ##  -0.63754 -0.16697 0.42696 -2.07473
= lm(dist ~ speed, data = cars) fit = coef(fit)b
|Estimate||Std. Error||t value||Pr(>|t|)|
The fitted regression equation is \(Y=-17.5791+3.9324x\).
par(mar=c(4, 4, 1, .1)) plot(cars, pch = 20) abline(fit, col = 'red')