Hello, Em 02-10-2012 19:18, Berend Hasselman escreveu:
On 02-10-2012, at 20:01, Rui Barradas <[email protected]> wrote:Hello, Yes, it's possible to remove the loop. Since the loop is used to compute a running product and all we want is the final result, use the vectorized behavior of R and a final ?prod(). Seedup: another 2x. And 4x2 == 8 == 1 [decimal] order of magnitude. lf2 <-function (x) { v<-1 x1 <- x[1] x2 <- x[2] x3 <- x[3] x4 <- x[4] z1 <- exp(x1+x2*dose) z2 <- exp(x3+x4*dose) psi0<-1/((1+z1)*(1+z2)) psi1<-z1*psi0 v <- (psi0^y0)*(psi1^y1)*((1-psi0-psi1)^y2) return( prod(v) ) } lf2.c <- cmpfun(lf2) Hope this helps,Wonderful. It certainly does help. A single nitpick: the v <- 1 at the start of the function can now be removed.
Yes, I thought about removing it but in the end forgot to.
I got a speedup of 7.5 compared to the very first version lf1.
My system is a Windows 7, R 2.15.1. Rui Barradas sessionInfo() R version 2.15.1 (2012-06-22) Platform: i386-pc-mingw32/i386 (32-bit) locale: [1] LC_COLLATE=Portuguese_Portugal.1252 LC_CTYPE=Portuguese_Portugal.1252 [3] LC_MONETARY=Portuguese_Portugal.1252 LC_NUMERIC=C [5] LC_TIME=Portuguese_Portugal.1252 attached base packages: [1] compiler stats graphics grDevices utils datasets methods [8] base other attached packages: [1] rbenchmark_1.0.0 cubature_1.1-1 loaded via a namespace (and not attached): [1] fortunes_1.5-0 tools_2.15.1
Berend
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