[R] summation sign

peter dalgaard pdalgd at gmail.com
Sat Oct 27 09:13:56 CEST 2012

On Oct 27, 2012, at 01:34 , sffarooqi wrote:

> Hi all,
> I have a very quick question on how to use the summation sign in R for the
> function.
> Here´s a basic example: the function is sum(i=1 to 5)log(1-xi^2)
> Id be grateful if someone knows how to do this without writing it out 5
> times - I am looking sth along the lines of  the following:
> computeR <- function(x)
>  {
>    return (-sum(log(1-x^2))
> }^
> thank you vm in advance!

You pretty much did it already:

> x <- c(.5,.6,.7,.4,.8)
> -sum(log(1-x^2))
[1] 2.603318

I.e., just have x as a vector of length 5 and the rest is done automagically.

(And, BTW, you don't need return() in a function like that in R, the return value is the value of the last expression.)

Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com

More information about the R-help mailing list