On Mon, Apr 18, 2011 at 10:41 AM, <luke-tier...@uiowa.edu> wrote: > The premise of your post is false: contrary to popular belief, R's > looping constructs are not particularly inefficient. Slowness of loops > relative to vectorized code comes from the cost of interpreting the > body of the loop. That exact same interpreter would be used to > interpret the bodies of functions used to express loops using > recursion, so it is not reasonable to expect this to improve > performance. In fact, due to the inefficiency of the current function > call mechanism in R, quite the opposite is true. > > As to the question: tail call optimization cannot be applied in R, at > least not in a simple way, because the semantics of R provide access > to the call stack via the sys.xyz functions and parent.frame and such. > It might be possible to make some semantic changes, such as only > guaranteeing access to the immediate caller, but there isn't much > point unless/until the performance of the function calling mechanism is > improved. > > Best, > > luke
To what extent does the recently introduced byte-code compilation help here? > On Sun, 17 Apr 2011, Mohit Dayal wrote: > >> Dear R-programmers, >> >> I am trying to program a Newton-Raphson in R (yes, i will try GSL, not >> right >> now), and it would be a real boon if R had tail call elimination, so that >> a >> recursive program has a guarantee not to fail due to stack overflows, >> given >> how slow loops in R are. I did look at the documentation, but could not >> find >> a reason for it. >> >> Regards, >> Mohit Dayal >> Researcher >> Applied Statistics & Computing Lab >> ISB >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> R-devel@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-devel >> > > -- > Luke Tierney > Statistics and Actuarial Science > Ralph E. Wareham Professor of Mathematical Sciences > University of Iowa Phone: 319-335-3386 > Department of Statistics and Fax: 319-335-3017 > Actuarial Science > 241 Schaeffer Hall email: l...@stat.uiowa.edu > Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel > ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
