[R] Ubuntu vs Mac OS X

[Guillaume Blanchet]

Hi !

I have installed R-2.7.0 64-bits on a computer where the new Ubuntu 
version (8.04) was installed. This computer is a 3.2 GHz Dual-core with 
2 Gb of RAM.

To test how fast (I though !) this machine is, I compared two simple 
matrix manipulations between Ubuntu and my laptop (a MacBook Pro 2.2 GHz 
with also 2 Gb of RAM under Mac OS X 10.5.2). By the way, I install the 
normal version of R on my MacBook Pro (32-bits)

I decided to use the following matrix manipulation because they are 
typical manipulation that I was planning to do repetitively and with 
much larger matrices for my PhD project.

First matrix manipulation:

coco<-matrix(rnorm(1000000),1000,1000)
system.time(coco2<-eigen(coco))

Results on the Mac:
user     system      elapsed
7.301       0.974       7.376

Results on Ubuntu:
user     system      elapsed
20.573       0.088       20.766

Second matrix manipulation:

coco<-matrix(rnorm(1000000),1000,1000)
system.time(coco3<-coco%*%coco)

Results on the Mac:
user     system      elapsed
0.360       0.024       0.224

Results on Ubuntu:
user     system      elapsed
2.756       0.000       2.758

If I understand these results right, my MacBook Pro is far better than 
this Desk computer. I know Macs are good but that difference of 
performance is surprising me, did I do something wrong considering the 
large difference in processor?

Thanks in advance

Guillaume Blanchet