292 lines
8.5 KiB
C++
292 lines
8.5 KiB
C++
/** nonfinite_num_facet.cpp
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*
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* Copyright (c) 2011 Francois Mauger
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* Copyright (c) 2011 Paul A. Bristow
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*
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* Distributed under the Boost Software License, Version 1.0.
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* (See accompanying file LICENSE_1_0.txt
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* or copy at http://www.boost.org/LICENSE_1_0.txt)
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*
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* This simple program illustrates how to use the
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* `boost/math/nonfinite_num_facets.hpp' material from the original
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* Floating Point Utilities contribution by Johan Rade.
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* Floating Point Utility library has been accepted into Boost,
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* but the utilities have been/will be incorporated into Boost.Math library.
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*
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\file
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\brief A fairly simple example of using non_finite_num facet for
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C99 standard output of infinity and NaN.
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\detail This program illustrates how to use the
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`boost/math/nonfinite_num_facets.hpp' material from the original
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Floating Point Utilities contribution by Johan Rade.
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Floating Point Utility library has been accepted into Boost,
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but the utilities have been/will be incorporated into Boost.Math library.
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Based on an example from Francois Mauger.
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Double and float variables are assigned ordinary finite values (pi),
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and nonfinite like infinity and NaN.
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These values are then output and read back in, and then redisplayed.
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*/
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#ifdef _MSC_VER
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# pragma warning(disable : 4127) // conditional expression is constant.
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#endif
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#include <iostream>
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#include <iomanip>
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using std::cout;
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using std::endl;
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#include <limits> // numeric_limits
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using std::numeric_limits;
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#include <boost/cstdint.hpp>
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#include <boost/math/special_functions/nonfinite_num_facets.hpp>
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static const char sep = ','; // Separator of bracketed float and double values.
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// Use max_digits10 (or equivalent) to obtain
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// all potentially significant decimal digits for the floating-point types.
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#ifdef BOOST_NO_CXX11_NUMERIC_LIMITS
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std::streamsize max_digits10_float = 2 + std::numeric_limits<float>::digits * 30103UL / 100000UL;
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std::streamsize max_digits10_double = 2 + std::numeric_limits<double>::digits * 30103UL / 100000UL;
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#else
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// Can use new C++0X max_digits10 (the maximum potentially significant digits).
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std::streamsize max_digits10_float = std::numeric_limits<float>::max_digits10;
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std::streamsize max_digits10_double = std::numeric_limits<double>::max_digits10;
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#endif
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/* A class with a float and a double */
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struct foo
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{
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foo () : fvalue (3.1415927F), dvalue (3.1415926535897931)
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{
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}
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// Set both the values to -infinity :
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void minus_infinity ()
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{
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fvalue = -std::numeric_limits<float>::infinity ();
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dvalue = -std::numeric_limits<double>::infinity ();
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return;
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}
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// Set the values to +infinity :
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void plus_infinity ()
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{
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fvalue = +std::numeric_limits<float>::infinity ();
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dvalue = +std::numeric_limits<double>::infinity ();
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return;
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}
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// Set the values to NaN :
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void nan ()
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{
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fvalue = +std::numeric_limits<float>::quiet_NaN ();
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dvalue = +std::numeric_limits<double>::quiet_NaN ();
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return;
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}
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// Print a foo:
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void print (std::ostream & a_out, const std::string & a_title)
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{
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if (a_title.empty ()) a_out << "foo";
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else a_out << a_title;
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a_out << " : " << std::endl;
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a_out << "|-- " << "fvalue = ";
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a_out.precision (max_digits10_float);
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a_out << fvalue << std::endl;
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a_out << "`-- " << "dvalue = ";
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a_out.precision (max_digits10_double);
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a_out << dvalue << std::endl;
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return;
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}
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// I/O operators for a foo structure of a float and a double :
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friend std::ostream & operator<< (std::ostream & a_out, const foo & a_foo);
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friend std::istream & operator>> (std::istream & a_in, foo & a_foo);
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// Attributes :
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float fvalue; // Single precision floating number.
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double dvalue; // Double precision floating number.
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};
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std::ostream & operator<< (std::ostream & a_out, const foo & a_foo)
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{ // Output bracketed FPs, for example "(3.1415927,3.1415926535897931)"
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a_out.precision (max_digits10_float);
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a_out << "(" << a_foo.fvalue << sep ;
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a_out.precision (max_digits10_double);
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a_out << a_foo.dvalue << ")";
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return a_out;
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}
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std::istream & operator>> (std::istream & a_in, foo & a_foo)
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{ // Input bracketed floating-point values into a foo structure,
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// for example from "(3.1415927,3.1415926535897931)"
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char c = 0;
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a_in.get (c);
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if (c != '(')
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{
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std::cerr << "ERROR: operator>> No ( " << std::endl;
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a_in.setstate(std::ios::failbit);
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return a_in;
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}
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float f;
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a_in >> std::ws >> f;
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if (! a_in)
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{
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return a_in;
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}
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a_in >> std::ws;
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a_in.get (c);
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if (c != sep)
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{
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std::cerr << "ERROR: operator>> c='" << c << "'" << std::endl;
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std::cerr << "ERROR: operator>> No '" << sep << "'" << std::endl;
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a_in.setstate(std::ios::failbit);
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return a_in;
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}
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double d;
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a_in >> std::ws >> d;
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if (! a_in)
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{
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return a_in;
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}
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a_in >> std::ws;
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a_in.get (c);
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if (c != ')')
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{
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std::cerr << "ERROR: operator>> No ) " << std::endl;
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a_in.setstate(std::ios::failbit);
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return a_in;
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}
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a_foo.fvalue = f;
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a_foo.dvalue = d;
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return a_in;
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} // std::istream & operator>> (std::istream & a_in, foo & a_foo)
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int main ()
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{
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std::cout << "nonfinite_num_facet simple example." << std::endl;
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if((std::numeric_limits<double>::has_infinity == false) || (std::numeric_limits<double>::infinity() == 0))
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{
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std::cout << "Infinity not supported on this platform." << std::endl;
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return 0;
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}
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if((std::numeric_limits<double>::has_quiet_NaN == false) || (std::numeric_limits<double>::quiet_NaN() == 0))
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{
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std::cout << "NaN not supported on this platform." << std::endl;
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return 0;
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}
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#ifdef BOOST_NO_CXX11_NUMERIC_LIMITS
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cout << "BOOST_NO_CXX11_NUMERIC_LIMITS is defined, so no max_digits10 available either:"
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"\n we'll have to calculate our own version." << endl;
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#endif
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std::cout << "std::numeric_limits<float>::max_digits10 is " << max_digits10_float << endl;
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std::cout << "std::numeric_limits<double>::max_digits10 is " << max_digits10_double << endl;
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std::locale the_default_locale (std::locale::classic ());
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{
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std::cout << "Write to a string buffer (using default locale) :" << std::endl;
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foo f0; // pi
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foo f1; f1.minus_infinity ();
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foo f2; f2.plus_infinity ();
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foo f3; f3.nan ();
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f0.print (std::cout, "f0"); // pi
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f1.print (std::cout, "f1"); // +inf
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f2.print (std::cout, "f2"); // -inf
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f3.print (std::cout, "f3"); // NaN
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std::ostringstream oss;
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std::locale C99_out_locale (the_default_locale, new boost::math::nonfinite_num_put<char>);
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oss.imbue (C99_out_locale);
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oss.precision (15);
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oss << f0 << f1 << f2 << f3;
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std::cout << "Output in C99 format is: \"" << oss.str () << "\"" << std::endl;
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std::cout << "Output done." << std::endl;
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}
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{
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std::string the_string = "(3.1415927,3.1415926535897931)(-inf,-inf)(inf,inf)(nan,nan)"; // C99 format
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// Must have correct separator!
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std::cout << "Read C99 format from a string buffer containing \"" << the_string << "\""<< std::endl;
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std::locale C99_in_locale (the_default_locale, new boost::math::nonfinite_num_get<char>);
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std::istringstream iss (the_string);
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iss.imbue (C99_in_locale);
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foo f0, f1, f2, f3;
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iss >> f0 >> f1 >> f2 >> f3;
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if (! iss)
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{
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std::cerr << "Input Format error !" << std::endl;
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}
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else
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{
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std::cerr << "Input OK." << std::endl;
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cout << "Display in default locale format " << endl;
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f0.print (std::cout, "f0");
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f1.print (std::cout, "f1");
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f2.print (std::cout, "f2");
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f3.print (std::cout, "f3");
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}
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std::cout << "Input done." << std::endl;
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}
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std::cout << "End nonfinite_num_facet.cpp" << std::endl;
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return 0;
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} // int main()
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// end of test_nonfinite_num_facets.cpp
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/*
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Output:
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nonfinite_num_facet simple example.
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std::numeric_limits<float>::max_digits10 is 8
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std::numeric_limits<double>::max_digits10 is 17
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Write to a string buffer (using default locale) :
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f0 :
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|-- fvalue = 3.1415927
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`-- dvalue = 3.1415926535897931
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f1 :
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|-- fvalue = -1.#INF
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`-- dvalue = -1.#INF
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f2 :
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|-- fvalue = 1.#INF
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`-- dvalue = 1.#INF
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f3 :
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|-- fvalue = 1.#QNAN
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`-- dvalue = 1.#QNAN
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Output in C99 format is: "(3.1415927,3.1415926535897931)(-inf,-inf)(inf,inf)(nan,nan)"
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Output done.
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Read C99 format from a string buffer containing "(3.1415927,3.1415926535897931)(-inf,-inf)(inf,inf)(nan,nan)"
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Display in default locale format
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f0 :
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|-- fvalue = 3.1415927
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`-- dvalue = 3.1415926535897931
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f1 :
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|-- fvalue = -1.#INF
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`-- dvalue = -1.#INF
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f2 :
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|-- fvalue = 1.#INF
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`-- dvalue = 1.#INF
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f3 :
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|-- fvalue = 1.#QNAN
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`-- dvalue = 1.#QNAN
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Input done.
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End nonfinite_num_facet.cpp
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*/
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