ceph/src/boost/libs/math/example/policy_eg_1.cpp

   1 //  Copyright John Maddock 2007.
   2 //  Copyright Paul A> Bristow 2010
   3 //  Use, modification and distribution are subject to the
   4 //  Boost Software License, Version 1.0. (See accompanying file
   5 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6
   7 #include <iostream>
   8 using std::cout; using std::endl;
   9 #include <cerrno> // for ::errno
  10
  11 //[policy_eg_1
  12
  13 #include <boost/math/special_functions/gamma.hpp>
  14 using boost::math::tgamma;
  15
  16 // Define the policy to use:
  17 using namespace boost::math::policies; // may be convenient, or
  18
  19 using boost::math::policies::policy;
  20 // Types of error whose action can be altered by policies:.
  21 using boost::math::policies::evaluation_error;
  22 using boost::math::policies::domain_error;
  23 using boost::math::policies::overflow_error;
  24 using boost::math::policies::domain_error;
  25 using boost::math::policies::pole_error;
  26 // Actions on error (in enum error_policy_type):
  27 using boost::math::policies::errno_on_error;
  28 using boost::math::policies::ignore_error;
  29 using boost::math::policies::throw_on_error;
  30 using boost::math::policies::user_error;
  31
  32 typedef policy<
  33    domain_error<errno_on_error>,
  34    pole_error<errno_on_error>,
  35    overflow_error<errno_on_error>,
  36    evaluation_error<errno_on_error>
  37 > c_policy;
  38 //
  39 // Now use the policy when calling tgamma:
  40
  41 // http://msdn.microsoft.com/en-us/library/t3ayayh1.aspx
  42 // Microsoft errno declared in STDLIB.H as "extern int errno;"
  43
  44 int main()
  45 {
  46    errno = 0; // Reset.
  47    cout << "Result of tgamma(30000) is: "
  48       << tgamma(30000, c_policy()) << endl; // Too big parameter
  49    cout << "errno = " << errno << endl; // errno 34 Numerical result out of range.
  50    cout << "Result of tgamma(-10) is: "
  51       << boost::math::tgamma(-10, c_policy()) << endl; // Negative parameter.
  52    cout << "errno = " << errno << endl; // error 33 Numerical argument out of domain.
  53 } // int main()
  54
  55 //]
  56
  57 /* Output
  58
  59 policy_eg_1.cpp
  60   Generating code
  61   Finished generating code
  62   policy_eg_1.vcxproj -> J:\Cpp\MathToolkit\test\Math_test\Release\policy_eg_1.exe
  63   Result of tgamma(30000) is: 1.#INF
  64   errno = 34
  65   Result of tgamma(-10) is: 1.#QNAN
  66   errno = 33
  67
  68 */
  69
  70