[Octave-bug-tracker] [bug #45461] binornd inefficient, patch attached

[anonymous]

URL:
  <http://savannah.gnu.org/bugs/?45461>

                 Summary: binornd inefficient, patch attached
                 Project: GNU Octave
            Submitted by: None
            Submitted on: Thu 02 Jul 2015 11:55:19 AM UTC
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Performance
                  Status: None
             Assigned to: None
         Originator Name: Michael Leitner
        Originator Email: address@hidden
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: Any

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Details:

The present implementation of binornd is very inefficient. For non-scalar N it
computes max(N(:))*numel(N) random values (and uses memory on the same order
of magnitude). The attached patch uses only sum(N(:)) random values. Of
course, the algorithm is still inefficient (one could work via the cdf), but
for a range of use cases it is perfectly usable in contrast to the old
implementation. 

Demonstration:

N=ones(10000,1);N(1)=10000;
tic;binornd(N,.5);toc


takes 2.4 s for the old and 0.008 s for the new one.



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File Attachments:


-------------------------------------------------------
Date: Thu 02 Jul 2015 11:55:19 AM UTC  Name: patch  Size: 1kB   By: None

<http://savannah.gnu.org/bugs/download.php?file_id=34360>

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