Le 08/10/2018 à 12:56, Dima Pasechnik a écrit : > On Mon, Oct 8, 2018 at 11:34 AM Thierry Dumont > <tdum...@math.univ-lyon1.fr> wrote: >> >> I do: >> >> N= 10^8 >> theta= RDF(2*pi/N) >> phi=[i*theta for i in range(0,N)] >> >> not something sophisticated...! >> >> Also: it is not a good idea do do that: better use numpy. BUT >> >> looking at "top" during the computation of >> phi=[i*theta for i in range(0,N)], >> the memory used jumps to 3Gb and then grows, grows... until it reaches >> the limits of my 8GB machine. >> >> python lists are not known to be very efficient, ok. But this is a bit >> too much, no ? > > If you limit the memory to 4GB you can do the same out of memory stunt > using plain python: > > $ ulimit -Sv 4000000 > $ ./sage --python > Python 2.7.15 (default, Sep 19 2018, 15:29:25) > [GCC 7.3.1 20180130 (Red Hat 7.3.1-2)] on linux2 > Type "help", "copyright", "credits" or "license" for more information. >>>> N=10**8 >>>> theta=6.283185307179586e-08 >>>> phi=[i*theta for i in range(0,N)] > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > MemoryError > > > Perhaps RDF takes more memory, I don't know - anyway, it's not > Sage-specific IMHO. > >> RDF are machine double floats; that is to say C "double", which take 8 bytes. So my list should use less than 1gb, if it phi was a C array. Am I wrong ?
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<<attachment: tdumont.vcf>>
