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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="math_toolkit.intro_pol_overview"></a><a class="link" href="intro_pol_overview.html" title="Policies">Policies</a>
</h2></div></div></div>
<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="pol_tutorial.html" title="Policy Tutorial">policy tutorial</a>
and the <a class="link" href="pol_ref.html" title="Policy Reference">policy reference</a>.
</p>
<p>
Generally speaking, unless you find that the <a class="link" href="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>
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>
Although the policy mechanism itself is rather complicated, in practice it
is easy to use, and very flexible.
</p>
<p>
Using policies you can control:
</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<a class="link" href="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 class="listitem">
How <a class="link" href="pol_ref/internal_promotion.html" title="Internal Floating-point Promotion Policies">accuracy is
controlled by internal promotion</a> to use more precise types.
</li>
<li class="listitem">
What working <a class="link" href="pol_ref/precision_pol.html" title="Precision Policies">precision</a>
should be used to calculate results.
</li>
<li class="listitem">
What to do when a <a class="link" href="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 class="listitem">
Whether <a class="link" href="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 class="listitem">
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#math_toolkit.error_handling.evaluation_error">evaluation_error</a>.
</li>
</ul></div>
<p>
You can control policies:
</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
Using <a class="link" href="pol_ref/policy_defaults.html" title="Using Macros to Change the Policy Defaults">macros</a>
to change any default policy: the is the preferred method for installation
wide policies.
</li>
<li class="listitem">
At your chosen <a class="link" href="pol_ref/namespace_pol.html" title="Setting Polices at Namespace Scope">namespace
scope</a> for distributions and/or functions: this is the preferred
method for project, namespace, or translation unit scope policies.
</li>
<li class="listitem">
In an ad-hoc manner <a class="link" href="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="pol_tutorial/ad_hoc_dist_policies.html" title="Setting Policies for Distributions on an Ad Hoc Basis">statistical
distribution</a>.
</li>
</ul></div>
</div>
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Lalande, John Maddock, Evan Miller, Jeremy Murphy, Matthew Pulver, Johan Råde,
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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