[R] ^ operation much slower in R 1.7.1 than in R 1.7.0 ???
Philippe Grosjean
phgrosjean at sciviews.org
Mon Aug 4 16:07:56 CEST 2003
I do not understand what happens here (under Win XP):
a <- abs(matrix(rnorm(800*800)/2, ncol=800, nrow=800))
system.time(b <- a^1000)[3]
took about 1 sec on my computer with R 1.7.0 and it takes now 4.59 sec with
R 1.7.1
Similarly,
phi <- 1.6180339887498949
a <- floor(runif(750000)*1000)
system.time(b <- (phi^a - (-phi)^(-a))/sqrt(5))[3]
took about 0.9 sec with R 1.7.0, and it takes 11.8 sec (!!!) in R 1.7.1.
Are there some changes made between 1.7.0 and 1.7.1 that could cause such a
large difference in time to do such simple computations???
Best,
Philippe Grosjean
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