Hello,
i am trying to compute the linear convolution of two vectors of length
1e7 each.
The code i am using is
a = vector(length=1e7)
b = vector(length=1e7)
#fill a and b with data...
c = convolve(a, rev(b), type="o")
Unfortunately, this computation goes on now for a very long time
(currently 15h and counting).
Does it make sense to wait a couple of hours more or do i only waste my
time and resources because it will take ages?
Is there maybe a better way to compute the convolution?
Or are there specific vector lengths that speed up the computation of
the convolution? I for example found out that convolving vectors of
length 1e5 takes 3 times longer than convolving vectors of size 4e6...
> b = vector(length=4e6)
> a = vector(length=4e6)
> system.time( convolve(a, b, type="o") )
user system elapsed
123.796 0.196 124.132
> a = vector(length=1e5)
> b = vector(length=1e5)
> system.time( convolve(a, b, type="o") )
user system elapsed
303.129 0.099 303.635
Best,
Philip
--
Philip Wette, M.Sc. E-Mail: we...@mail.upb.de
University of Paderborn Tel.: 05251 / 60-1716
Department of Computer Science
Computer Networks Group http://wwwcs.upb.de/cs/ag-karl
Warburger Straße 100 Room: O3.152
33098 Paderborn
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