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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 18:24:20 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 18:24:20 +0000
commit483eb2f56657e8e7f419ab1a4fab8dce9ade8609 (patch)
treee5d88d25d870d5dedacb6bbdbe2a966086a0a5cf /src/boost/libs/math/example/policy_ref_snip1.cpp
parentInitial commit. (diff)
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Adding upstream version 14.2.21.upstream/14.2.21upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/boost/libs/math/example/policy_ref_snip1.cpp')
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diff --git a/src/boost/libs/math/example/policy_ref_snip1.cpp b/src/boost/libs/math/example/policy_ref_snip1.cpp
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+// Copyright John Maddock 2007.
+// Copyright Paul A. Bristow 2010.
+// Use, modification and distribution are subject to the
+// Boost Software License, Version 1.0. (See accompanying file
+// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+// Note that this file contains quickbook mark-up as well as code
+// and comments, don't change any of the special comment mark-ups!
+
+//[policy_ref_snip1
+
+#include <boost/math/special_functions/gamma.hpp>
+using boost::math::tgamma;
+
+//using namespace boost::math::policies; may also be convenient.
+using boost::math::policies::policy;
+using boost::math::policies::evaluation_error;
+using boost::math::policies::domain_error;
+using boost::math::policies::overflow_error;
+using boost::math::policies::domain_error;
+using boost::math::policies::pole_error;
+using boost::math::policies::errno_on_error;
+
+// Define a policy:
+typedef policy<
+ domain_error<errno_on_error>,
+ pole_error<errno_on_error>,
+ overflow_error<errno_on_error>,
+ evaluation_error<errno_on_error>
+> my_policy;
+
+double my_value = 0.; //
+
+// Call the function applying my_policy:
+double t1 = tgamma(my_value, my_policy());
+
+// Alternatively (and equivalently) we could use helpful function
+// make_policy and define everything at the call site:
+double t2 = tgamma(my_value,
+ make_policy(
+ domain_error<errno_on_error>(),
+ pole_error<errno_on_error>(),
+ overflow_error<errno_on_error>(),
+ evaluation_error<errno_on_error>() )
+ );
+//]
+
+#include <iostream>
+using std::cout; using std::endl;
+
+int main()
+{
+ cout << "my_value = " << my_value << endl;
+ try
+ { // First with default policy - throw an exception.
+ cout << "tgamma(my_value) = " << tgamma(my_value) << endl;
+ }
+ catch(const std::exception& e)
+ {
+ cout <<"\n""Message from thrown exception was:\n " << e.what() << endl;
+ }
+
+ cout << "tgamma(my_value, my_policy() = " << t1 << endl;
+ cout << "tgamma(my_value, make_policy(domain_error<errno_on_error>(), pole_error<errno_on_error>(), overflow_error<errno_on_error>(), evaluation_error<errno_on_error>() ) = " << t2 << endl;
+}
+
+/*
+Output:
+ my_value = 0
+
+ Message from thrown exception was:
+ Error in function boost::math::tgamma<long double>(long double): Evaluation of tgamma at a negative integer 0.
+ tgamma(my_value, my_policy() = 1.#QNAN
+ tgamma(my_value, make_policy(domain_error<errno_on_error>(), pole_error<errno_on_error>(), overflow_error<errno_on_error>(), evaluation_error<errno_on_error>() ) = 1.#QNAN
+*/