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[ceph.git] / ceph / src / boost / libs / math / example / lambert_w_basic_example.cpp

diff --git a/ceph/src/boost/libs/math/example/lambert_w_basic_example.cpp b/ceph/src/boost/libs/math/example/lambert_w_basic_example.cpp
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+// Copyright Paul A. Bristow 2018
+
+// Distributed under 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)
+
+// Example of most basic call of both lambert W functions.
+// Only requires C++03 
+// (and optionally a call of max_digits10 to show precision).
+
+#include <boost/math/special_functions/lambert_w.hpp> // For lambert_w0 and wm1 functions.
+
+#include <iostream>
+#include <iomanip>
+
+int main()
+{
+  double z = 2.0;
+  double w0 = boost::math::lambert_w0(z);
+  std::cout.setf(std::ios_base::showpoint); // Include any trailing zeros.
+  std::cout.precision(std::numeric_limits<double>::max_digits10); // Show all possibly significant digits.
+  // Avoid using max_digfigs10 so as many old compilers can run the most basic lambert_w0 test?
+  // Require to get max_digits10
+  //   [ run lambert_w_basic_example.cpp  : : : [ requires cxx11_numeric_limits ] ]
+  std::cout << " lambert_w0(" << z << ") = " << w0 << std::endl; // lambert_w0(2.00000) = 0.852606
+  z = -0.2;
+  double wm1 = boost::math::lambert_wm1(z);
+  std::cout << " lambert_wm1(" << z << ") = " << wm1 << std::endl; // lambert_wm1(-0.200000) = -2.54264
+  return 0;
+} // int main()