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56 lines
1.4 KiB
C++
56 lines
1.4 KiB
C++
// Copyright John Maddock 2007.
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// Copyright Paul A. Bristow 2010
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// Use, modification and distribution are subject to the
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// Boost Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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// Note that this file contains quickbook mark-up as well as code
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// and comments, don't change any of the special comment mark-ups!
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// Define tgamma function with a no overflow policy
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// into a specific namespace-scope.
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#include <iostream>
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using std::cout; using std::endl;
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//[policy_ref_snip12
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#include <boost/math/special_functions/gamma.hpp>
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//using boost::math::tgamma;
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// Need not declare using boost::math::tgamma here,
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// because will define tgamma in myspace using macro below.
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namespace myspace
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{
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using namespace boost::math::policies;
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// Define a policy that does not throw on overflow:
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typedef policy<overflow_error<errno_on_error> > my_policy;
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// Define the special functions in this scope to use the policy:
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BOOST_MATH_DECLARE_SPECIAL_FUNCTIONS(my_policy)
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}
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// Now we can use myspace::tgamma etc.
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// They will automatically use "my_policy":
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//
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double t = myspace::tgamma(30.0); // Will *not* throw on overflow,
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// despite the large value of factorial 30 = 265252859812191058636308480000000
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// unlike default policy boost::math::tgamma;
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//]
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int main()
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{
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cout << "myspace::tgamma(30.0) = " << t << endl;
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}
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/*
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Output:
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myspace::tgamma(30.0) = 8.84176e+030
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*/
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