Dear list, According to this presentation ( http://www.rinfinance.com/agenda/2010/MarkSeligman_Tutorial.pdf), gpuHclust in the gputools package should be about 20x faster than clust, but after some testing, I find it actually 4x slower. Here is the code: test.data <- function(dim, num, seed=17) { set.seed(seed) matrix(rnorm(dim * num), nrow=num) } m <- test.data(1920, 9500) library(gputools) d <- gpuDist(m) # Euclidean distance system.time(gpuHclust(d)) user system elapsed 28.230 41.283 69.727 system.time(hclust(d)) user system elapsed 6.517 0.260 6.790 The gpu on my machine is Telsa C5020 from NVIDIA. Best regards, Kaiyin ZHONG ------------------------------ FMB, Erasmus MC k.zhong@erasmusmc.nl kindlychung@gmail.com [[alternative HTML version deleted]]