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memory_test.html
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<html>
<head>
<title>
MEMORY_TEST - How Big Can Arrays Be?
</title>
</head>
<body bgcolor="#EEEEEE" link="#CC0000" alink="#FF3300" vlink="#000055">
<h1 align = "center">
MEMORY_TEST <br> How Big Can Arrays Be?
</h1>
<hr>
<p>
<b>MEMORY_TEST</b>
is a MATLAB program which
declares and uses a sequence of larger and larger arrays,
to see what the memory limits are on a given computer.
</p>
<p>
The program tries an increasing series of values of <b>N</b>, using
powers of 2, between limits that you set. At some point, the program
may ask for more memory than can be provided, and crash. This is one
way to find out what the memory ceiling is! The relevant power of 2
is likely to be in the 20's:
<table border="1">
<tr>
<th>Log(N)</th><th>N</th>
</tr>
<tr>
<td>20</td><td>1,048,576</td>
</tr>
<tr>
<td>21</td><td>2,097,152</td>
</tr>
<tr>
<td>22</td><td>4,194,304</td>
</tr>
<tr>
<td>23</td><td>8,388,608</td>
</tr>
<tr>
<td>24</td><td>16,777,216</td>
</tr>
<tr>
<td>25</td><td>33,554,432</td>
</tr>
<tr>
<td>26</td><td>67,108,864</td>
</tr>
<tr>
<td>27</td><td>134,217,728</td>
</tr>
<tr>
<td>28</td><td>268,435,456</td>
</tr>
<tr>
<td>29</td><td>536,870,912</td>
</tr>
<tr>
<td>30</td><td>1,073,741,824</td>
</tr>
</table>
</p>
<p>
Remember that your memory is probably described in terms of bytes,
but that integers and reals require 4 bytes, and double precision reals
require 8 bytes.
</p>
<h3 align = "center">
Usage:
</h3>
<p>
<blockquote>
<b>memory_test</b> ( <i>log_n_min</i>, <i>log_n_max</i> )
</blockquote>
runs the program for sizes <b>N</b> = 2<sup>log_n_min</sup> to
2<sup>log_n_max</sup>.
</p>
<h3 align = "center">
Licensing:
</h3>
<p>
The computer code and data files described and made available on this web page
are distributed under
<a href = "../../txt/gnu_lgpl.txt">the GNU LGPL license.</a>
</p>
<h3 align = "center">
Languages:
</h3>
<p>
<b>MEMORY_TEST</b> is available in
<a href = "../../c_src/memory_test/memory_test.html">a C version</a> and
<a href = "../../cpp_src/memory_test/memory_test.html">a C++ version</a> and
<a href = "../../f_src/memory_test/memory_test.html">a FORTRAN90 version</a> and
<a href = "../../m_src/memory_test/memory_test.html">a MATLAB version</a>.
</p>
<h3 align = "center">
Related Data and Programs:
</h3>
<p>
<a href = "../../m_src/linpack_bench/linpack_bench.html">
LINPACK_BENCH</a>,
a MATLAB program which
measures the time needed to factor and solve a linear system.
</p>
<p>
<a href = "../../m_src/machine/machine.html">
MACHINE</a>,
a MATLAB library which
can return various machine constants.
</p>
<p>
<a href = "../../f_src/matmul/matmul.html">
MATMUL</a>,
a FORTRAN90 program which
is an interactive
matrix multiplication benchmark program.
</p>
<p>
<a href = "../../f77_src/mdbnch/mdbnch.html">
MDBNCH</a>,
a FORTRAN77 program which
is a benchmark code for a molecular dynamics calculation.
</p>
<p>
<a href = "../../m_src/sum_million/sum_million.html">
SUM_MILLION</a>,
a MATLAB program which
sums the integers from 1 to 1,000,000, as a demonstration of how
to rate a computer's speed;
</p>
<p>
<a href = "../../m_src/timer/timer.html">
TIMER</a>,
a MATLAB program which
demonstrates how to compute CPU time or elapsed time.
</p>
<h3 align = "center">
Source Code:
</h3>
<p>
<ul>
<li>
<a href = "memory_test.m">memory_test.m</a>,
the source code.
</li>
</ul>
</p>
<h3 align = "center">
Examples and Tests:
</h3>
<p>
<ul>
<li>
<a href = "memory_test_output_g5.txt">memory_test_output_g5.txt</a>,
a run of the program on a Mac, up to LOG(N) = 26.
</li>
<li>
<a href = "memory_test_output_pc.txt">memory_test_output_pc.txt</a>,
a run of the program on a PC, up to LOG(N) = 25.
</li>
</ul>
</p>
<p>
You can go up one level to <a href = "../m_src.html">
the MATLAB source codes</a>.
</p>
<hr>
<i>
Last revised on 30 June 2009.
</i>
<!-- John Burkardt -->
</body>
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</html>