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<html>
<head>
<title>
IHS_DATASET - Generate IHS Datasets
</title>
</head>
<body bgcolor="#EEEEEE" link="#CC0000" alink="#FF3300" vlink="#000055">
<h1 align = "center">
IHS_DATASET <br> Generate IHS Datasets
</h1>
<hr>
<p>
<b>IHS_DATASET</b>
is a C++ program which
creates an IHS (Improved Hypercube Sampling) dataset.
</p>
<p>
A Latin hypercube, in <b>M</b> dimensional space, with <b>N</b> points,
can be thought of as being constructed by dividing each of the
<b>M</b> coordinate dimensions into <b>N</b> equal intervals. The
J-th coordinate of the I-th point can be constructed by choosing, in
the J-th dimension, an interval that has not been used, and then
choosing any value in that interval.
</p>
<p>
This algorithm differs in that it tries to pick a solution
which has the property that the points are "spread out"
as evenly as possible. It does this by determining an optimal
even spacing, and using the duplication factor D to allow it
to choose the best of the various options available to it
(the more duplication, the better chance of optimization).
</p>
<p>
One drawback to this algorithm is that it requires an internal
real distance array of dimension D * N * N. For a relatively moderate
problem with N = 1000, this can exceed the easily accessible
memory. Moreover, the program is inherently quadratic in N
in execution time as well as memory; the computation of the I-th
point in the set of N requires a consideration of the value of
the coordinates used up by the previous points, and the distances
from each of those points to the candidates for the next point.
</p>
<p>
The program is interactive, and allows the user to choose
<ul>
<li>
<b>M</b>, the spatial dimension;
</li>
<li>
<b>N</b>, the number of points to generate;
</li>
<li>
<b>D</b>, the duplication factor.
</li>
<li>
<b>SEED</b>, a seed for UNIFORM, the portable uniform random
number generator used to make choices.
</li>
</ul>
Once these parameters are set, the program generates the data,
and writes it to a file. The user may then specify another
set of data, or terminate the program.
</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>IHS_DATASET</b> is available in
<a href = "../../cpp_src/ihs_dataset/ihs_dataset.html">a C++ version</a> and
<a href = "../../f_src/ihs_dataset/ihs_dataset.html">a FORTRAN90 version</a> and
<a href = "../../m_src/ihs_dataset/ihs_dataset.html">a MATLAB version</a>.
</p>
<h3 align = "center">
Related Data and Programs:
</h3>
<p>
<a href = "../../cpp_src/faure_dataset/faure_dataset.html">
FAURE_DATASET</a>,
a C++ program which
creates a Faure quasirandom dataset;
</p>
<p>
<a href = "../../cpp_src/grid_dataset/grid_dataset.html">
GRID_DATASET</a>,
a C++ program which
creates a grid sequence and writes it to a file.
</p>
<p>
<a href = "../../cpp_src/ihs/ihs.html">
IHS</a>,
a C++ library which
supplies the computational routines needed by
IHS_DATASET.
</p>
<p>
<a href = "../../datasets/ihs/ihs.html">
IHS</a>,
a dataset directory which
contains sample datasets created
by <b>IHS_DATASET</b>.
</p>
<p>
<a href = "../../cpp_src/latin_center_dataset/latin_center_dataset.html">
LATIN_CENTER_DATASET</a>,
a C++ program which
creates a Latin Center Hypercube dataset;
</p>
<p>
<a href = "../../cpp_src/latin_edge_dataset/latin_edge_dataset.html">
LATIN_EDGE_DATASET</a>,
a C++ program which
creates a Latin Edge Hypercube dataset;
</p>
<p>
<a href = "../../cpp_src/latin_random_dataset/latin_random_dataset.html">
LATIN_RANDOM_DATASET</a>,
a C++ program which
creates a Latin Random Hypercube dataset;
</p>
<p>
<a href = "../../cpp_src/niederreiter2_dataset/niederreiter2_dataset.html">
NIEDERREITER2_DATASET</a>,
a C++ program which
creates a Niederreiter quasirandom dataset with base 2;
</p>
<p>
<a href = "../../cpp_src/normal_dataset/normal_dataset.html">
NORMAL_DATASET</a>,
a C++ program which
generates a dataset of multivariate normal pseudorandom values and writes them to a file.
</p>
<p>
<a href = "../../cpp_src/sobol_dataset/sobol_dataset.html">
SOBOL_DATASET</a>,
a C++ program which
computes a Sobol quasirandom sequence and writes it to a file.
</p>
<p>
<a href = "../../cpp_src/uniform_dataset/uniform_dataset.html">
UNIFORM_DATASET</a>,
a C++ program which
generates a dataset of uniform pseudorandom values and writes them to a file.
</p>
<p>
<a href = "../../cpp_src/van_der_corput_dataset/van_der_corput_dataset.html">
VAN_DER_CORPUT_DATASET</a>,
a C++ program which
creates a van der Corput quasirandom sequence and writes it to a file.
</p>
<h3 align = "center">
Reference:
</h3>
<p>
<ol>
<li>
Brian Beachkofski, Ramana Grandhi,<br>
Improved Distributed Hypercube Sampling,<br>
American Institute of Aeronautics and Astronautics Paper 2002-1274.
</li>
</ol>
</p>
<h3 align = "center">
Source Code:
</h3>
<p>
<ul>
<li>
<a href = "ihs_dataset.cpp">ihs_dataset.cpp</a>,
the source code.
</li>
<li>
<a href = "ihs_dataset.sh">ihs_dataset.sh</a>,
commands to compile and load the source code.
</li>
</ul>
</p>
<h3 align = "center">
Examples and Tests:
</h3>
<p>
<ul>
<li>
<a href = "ihs_02_10_5_123456789.txt">ihs_02_10_5_123456789.txt</a>,
the data file created for M = 2, N = 10, D = 5, SEED = 123456789.
</li>
</ul>
</p>
<h3 align = "center">
List of Routines:
</h3>
<p>
<ul>
<li>
<b>MAIN</b> is the main program for IHS_DATASET.
</li>
</ul>
</p>
<p>
You can go up one level to <a href = "../cpp_src.html">
the C++ source codes</a>.
</p>
<hr>
<i>
Last revised on 31 August 2005.
</i>
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