Here's a small R program:
---------------------------------------------------------------------------
a <- rep(1,10000000)
system.time(a <- a + 1)
system.time(for (i in 1:10000000) {a[i] <- a[i] + 1})
---------------------------------------------------------------------------
and here's its matlab version:
---------------------------------------------------------------------------
function forloop()
a = ones(1e7,1);
tic; a = a + 1; toc
tic
for i=1:1e7
a(i) = a(i) + 1;
end
toc
---------------------------------------------------------------------------
The machine used for testing was an i386 core 2 duo machine at 2.2
GHz, running OS X `Tiger'. The R was 2.8.0 and the matlab was 2008a.
Here's the performance (time taken in seconds):
Matlab R Times
Vector version 0.0446 0.067 1.5x
For loop version 0.0992 42.209 425.5x
So the R is 1.5x costlier for the vector version and 425.5x costlier
with matlab.
I wonder what we're doing wrong!
--
Ajay Shah http://www.mayin.org/ajayshah
ajays...@mayin.org http://ajayshahblog.blogspot.com
<*(:-? - wizard who doesn't know the answer.
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