Dear all,
Recently I stumbled upon a very efficient C++ code which allows for fast
drawing a random sample of unique integers from within a given range.
The code is by Jon Bentley,
http://netlib.bell-labs.com/cm/cs/pearls/code.html (yes, THIS Bentley).
Since the webpage says "You may use this code for any purpose, as long
as you leave the copyright notice and book citation attached", I have
written a small Oct-file which implements this functionality into
Octave, see
main/miscellaneous/src/sample.cc
As suggested long time ago by Paul Kienzle, sample() can serve as a
basis for an improved sprand.m, which presently sometimes suffers from
returning matrices of slightly lower density than requested. I prepared
a new version of sprand, which utilizes sample() and indeed does a
better job in a reasonable time. The code is in
main/linear-algebra/inst/sprand.m
(well, the function best fits the "sparse" category, but this one
disappeared some time ago).
With best regards,
Piotr Krzyzanowski
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