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<div class="titlepage"><div><div><h3 class="title">
<a name="math_toolkit.main_overview.pol_overview"></a><a class="link" href="pol_overview.html" title="Configuration and Policies"> Configuration
and Policies</a>
</h3></div></div></div>
<p>
</p>
<p>
Policies are a powerful fine-grain mechanism that allow you to customise
the behaviour of this library according to your needs. There is more information
available in the <a class="link" href="../policy/pol_tutorial.html" title="Policy Tutorial">policy
tutorial</a> and the <a class="link" href="../policy/pol_ref.html" title="Policy Reference">policy
reference</a>.
</p>
<p>
</p>
<p>
Generally speaking unless you find that the <a class="link" href="../policy/pol_tutorial/policy_tut_defaults.html" title="Policies Have Sensible Defaults">default
policy behaviour</a> when encountering 'bad' argument values does not
meet your needs, you should not need to worry about policies.
</p>
<p>
</p>
<p>
Policies are a compile-time mechanism that allow you to change error-handling
or calculation precision either program wide, or at the call site.
</p>
<p>
</p>
<p>
Although the policy mechanism itself is rather complicated, in practice
it is easy to use, and very flexible.
</p>
<p>
</p>
<p>
Using policies you can control:
</p>
<p>
</p>
<div class="itemizedlist"><ul type="disc">
<li>
<a class="link" href="../policy/pol_ref/error_handling_policies.html" title="Error Handling Policies">How
results from 'bad' arguments are handled</a>, including those that
cannot be fully evaluated.
</li>
<li>
How <a class="link" href="../policy/pol_ref/internal_promotion.html" title="Internal Promotion Policies">accuracy
is controlled by internal promotion</a> to use more precise types.
</li>
<li>
What working <a class="link" href="../policy/pol_ref/precision_pol.html" title="Precision Policies">precision</a>
should be used to calculate results.
</li>
<li>
What to do when a <a class="link" href="../policy/pol_ref/assert_undefined.html" title="Mathematically Undefined Function Policies">mathematically
undefined function</a> is used: Should this raise a run-time or
compile-time error?
</li>
<li>
Whether <a class="link" href="../policy/pol_ref/discrete_quant_ref.html" title="Discrete Quantile Policies">discrete
functions</a>, like the binomial, should return real or only integral
values, and how they are rounded.
</li>
<li>
How many iterations a special function is permitted to perform in a
series evaluation or root finding algorithm before it gives up and
raises an <a class="link" href="error_handling.html#evaluation_error">evaluation_error</a>.
</li>
</ul></div>
<p>
</p>
<p>
You can control policies:
</p>
<p>
</p>
<div class="itemizedlist"><ul type="disc">
<li>
Using <a class="link" href="../policy/pol_ref/policy_defaults.html" title="Using macros to Change the Policy Defaults">macros</a>
to change any default policy: the is the prefered method for installation
wide policies.
</li>
<li>
At your chosen <a class="link" href="../policy/pol_ref/namespace_pol.html" title="Setting Polices at Namespace Scope">namespace
scope</a> for distributions and/or functions: this is the prefered
method for project, namespace, or translation unit scope policies.
</li>
<li>
In an ad-hoc manner <a class="link" href="../policy/pol_tutorial/ad_hoc_sf_policies.html" title="Changing the Policy on an Ad Hoc Basis for the Special Functions">by
passing a specific policy to a special function</a>, or to a <a class="link" href="../policy/pol_tutorial/ad_hoc_dist_policies.html" title="Setting Policies for Distributions on an Ad Hoc Basis">statistical
distribution</a>.
</li>
</ul></div>
<p>
</p>
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<td align="right"><div class="copyright-footer">Copyright © 2006 , 2007, 2008, 2009 John Maddock, Paul A. Bristow,
Hubert Holin, Xiaogang Zhang, Bruno Lalande, Johan Råde, Gautam Sewani
and Thijs van den Berg<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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