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163 | 163 | <div class="section" id="py-bobyqa-derivative-free-optimizer-for-bound-constrained-minimization">
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164 | 164 | <h1>Py-BOBYQA: Derivative-Free Optimizer for Bound-Constrained Minimization<a class="headerlink" href="#py-bobyqa-derivative-free-optimizer-for-bound-constrained-minimization" title="Permalink to this headline">¶</a></h1>
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165 | 165 | <p><strong>Release:</strong> 1.1</p>
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166 |
| -<p><strong>Date:</strong> 24 December 2018</p> |
| 166 | +<p><strong>Date:</strong> 07 January 2019</p> |
167 | 167 | <p><strong>Author:</strong> <a class="reference external" href="mailto:lindon.roberts%40maths.ox.ac.uk">Lindon Roberts</a></p>
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168 | 168 | <p>Py-BOBYQA is a flexible package for finding local solutions to nonlinear, nonconvex minimization problems (with optional bound constraints), without requiring any derivatives of the objective. Py-BOBYQA is a Python implementation of the <a class="reference external" href="http://mat.uc.pt/~zhang/software.html#powell_software">BOBYQA</a> solver by Powell (documentation <a class="reference external" href="http://www.damtp.cam.ac.uk/user/na/NA_papers/NA2009_06.pdf">here</a>). It is particularly useful when evaluations of the objective function are expensive and/or noisy.</p>
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169 | 169 | <p>That is, Py-BOBYQA solves</p>
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170 | 170 | <div class="math">
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171 | 171 | \[\begin{split}\min_{x\in\mathbb{R}^n} &\quad f(x)\\
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172 | 172 | \text{s.t.} &\quad a \leq x \leq b\end{split}\]</div>
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173 |
| -<p>Full details of the Py-BOBYQA algorithm are given in our paper: C. Cartis, J. Fiala, B. Marteau and L. Roberts, <a class="reference external" href="https://arxiv.org/abs/1804.00154">Improving the Flexibility and Robustness of Model-Based Derivative-Free Optimization Solvers</a>, technical report, University of Oxford, (2018).</p> |
| 173 | +<p>Full details of the Py-BOBYQA algorithm are given in our papers:</p> |
| 174 | +<ol class="arabic simple"> |
| 175 | +<li><ol class="first upperalpha" start="3"> |
| 176 | +<li>Cartis, J. Fiala, B. Marteau and L. Roberts, <a class="reference external" href="https://arxiv.org/abs/1804.00154">Improving the Flexibility and Robustness of Model-Based Derivative-Free Optimization Solvers</a>, technical report, University of Oxford, (2018).</li> |
| 177 | +</ol> |
| 178 | +</li> |
| 179 | +<li><ol class="first upperalpha" start="3"> |
| 180 | +<li>Cartis, L. Roberts and O. Sheridan-Methven, <a class="reference external" href="https://arxiv.org/abs/1812.11343">Escaping local minima with derivative-free methods: a numerical investigation</a>, technical report, University of Oxford, (2018).</li> |
| 181 | +</ol> |
| 182 | +</li> |
| 183 | +</ol> |
| 184 | +<p>Please cite [1] when using Py-BOBYQA for local optimization, and [1,2] when using Py-BOBYQA’s global optimization heuristic functionality <strong>(new in v1.1!)</strong>.</p> |
174 | 185 | <p>If you are interested in solving least-squares minimization problems, you may wish to try <a class="reference external" href="https://github.com/numericalalgorithmsgroup/dfols">DFO-LS</a>, which has the same features as Py-BOBYQA (plus some more), and exploits the least-squares problem structure, so performs better on such problems.</p>
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175 |
| -<p><strong>New feature: global optimization heuristic (July 2018)!</strong> Py-BOBYQA now has a heuristic for global optimization (see <a class="reference internal" href="userguide.html"><span class="doc">Using Py-BOBYQA</span></a> for details). As this is a heuristic, there are no guarantees it will find a global minimum, but it is more likely to escape local minima if there are better values nearby.</p> |
| 186 | +<p>Since v1.1, Py-BOBYQA has a heuristic for global optimization (see <a class="reference internal" href="userguide.html"><span class="doc">Using Py-BOBYQA</span></a> for details). As this is a heuristic, there are no guarantees it will find a global minimum, but it is more likely to escape local minima if there are better values nearby.</p> |
176 | 187 | <p>Py-BOBYQA is released under the GNU General Public License. Please <a class="reference external" href="http://www.nag.com/content/worldwide-contact-information">contact NAG</a> for alternative licensing.</p>
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177 | 188 | <div class="toctree-wrapper compound">
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178 | 189 | <p class="caption"><span class="caption-text">Contents:</span></p>
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