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POHow to avoid Matlab taking exponential time when creating a handle object array as an object property
 

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  1. POHow to avoid Matlab taking exponential time when creating a handle object array as an object property
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    <p>It seems to me that when creating an <strong>array of simple handle objects in Matlab time scales about linear</strong>. However, if I create exactly the same array and <strong>store it as a property of an object, time scales exponentially</strong> - so the program gets very slow when many objects are created.</p> <p><strong>My question is why this is happening and how it can be avoided?</strong> Is the pre-allocation for object properties not properly implemented in my code or is there a fundamental problem with the way Matlab handles these things?</p> <p>I wrote a simple test to illustrate the issue:</p> <p><strong>Code of simple Object:</strong></p> <pre><code>classdef SomeSimpleObject &lt; handle % SomeSimpleObject defines an Object that has one property properties property=0; end methods function SimpleObj=SomeSimpleObject() if nargin~=0 SimpleObj.property=1; end end end end </code></pre> <p><strong>Using the following Script to create a 1x10.000 array of these simple objects takes according to the profiler 0,4 sec on my machine:</strong></p> <pre><code>for n=10000:-1:1 % counting backwards for Memory pre-allocation ObjectList(n)=SomeSimpleObject(); end </code></pre> <p><strong>However doing the same thing inside a class constructor and storing the array of 10.000 objects as a property takes 59 sec and it gets much worse quickly. Try it by creating an object from this class (e.g. <em>a=HostingObject</em>)</strong></p> <pre><code>classdef HostingObject &lt; handle % This Objects Hosts a List of Objects that are created in the % constructor properties ObjectList=SomeSimpleObject end methods function obj=HostingObject() for n=10000:-1:1 % counting backwards for Memory pre-allocation obj.ObjectList(n)=SomeSimpleObject(); end end end end </code></pre> <p>Searching for an Answer I came across a discussion on Matlab memory allocation and <a href="https://stackoverflow.com/questions/1446281/matlabs-garbage-collector">garbage collection</a>. The Answer of Mikhail (also not directly related to my question) made me think that it might be a fundamental problem with the way Matlab implements objects, but I'm still not sure.</p>
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    1. USJacob
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    1. CONote to readers: see also [Jacobs' previous related question](http://stackoverflow.com/questions/7676162/slow-performance-when-storing-handle-objects-in-a-cell-array) which spurred this one
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    2. COI think that you are pushing MATLAB to the limit, MATLAB was not developed for this kind of usage. After I got burned with MATLAB GC http://stackoverflow.com/questions/1446281/matlabs-garbage-collector I gone C# and since never looked behind - http://stackoverflow.com/questions/5042761/matlab-programming-best-practices/5050674#5050674
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