Something like this? f <- function(x) x^3-2*x curve(f(x), from=0, to=4) abline(h=0) n <- 16 dx <- 4/n right <- (1:n)*dx left <- right - dx mid <- right - dx/2 fm <- f(mid) points(mid, fm) rect(left,0,right,fm)
sum(fm*dx) 1/4 * 4^4 - 4^2 -pd On 27 Nov 2015, at 13:52 , Steven Stoline <sstol...@gmail.com> wrote: > Dear All: > > I am trying to explain to my students how to calculate the definite > integral using the Riemann sum. Can someone help me to graph the area under > the curve of the function, showing the curve as well as the rectangles > between 0 and 4.. > > *f(x) = x^3 - 2*x * > > over the interval [0 , 4] > > > > with many thanks > steve > > -- > Steven M. Stoline > 1123 Forest Avenue > Portland, ME 04112 > sstol...@gmail.com > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. -- Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Office: A 4.23 Email: pd....@cbs.dk Priv: pda...@gmail.com ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
