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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/lambert_w_graph.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>
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+// Copyright Paul A. Bristow 2017
+// Copyright John Z. Maddock 2017
+
+// 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).
+
+/*! \brief Graph showing use of Lambert W function.
+
+\details
+
+Both Lambert W0 and W-1 branches can be shown on one graph.
+But useful to have another graph for larger values of argument z.
+Need two separate graphs for Lambert W0 and -1 prime because
+the sensible ranges and axes are too different.
+
+One would get too small LambertW0 in top right and W-1 in bottom left.
+
+*/
+
+#include <boost/math/special_functions/lambert_w.hpp>
+using boost::math::lambert_w0;
+using boost::math::lambert_wm1;
+using boost::math::lambert_w0_prime;
+using boost::math::lambert_wm1_prime;
+
+#include <boost/math/special_functions.hpp>
+using boost::math::isfinite;
+#include <boost/svg_plot/svg_2d_plot.hpp>
+using namespace boost::svg;
+#include <boost/svg_plot/show_2d_settings.hpp>
+using boost::svg::show_2d_plot_settings;
+
+#include <iostream>
+// using std::cout;
+// using std::endl;
+#include <exception>
+#include <stdexcept>
+#include <string>
+#include <array>
+#include <vector>
+#include <utility>
+using std::pair;
+#include <map>
+using std::map;
+#include <set>
+using std::multiset;
+#include <limits>
+using std::numeric_limits;
+#include <cmath> //
+
+ /*!
+ */
+int main()
+{
+ try
+ {
+ std::cout << "Lambert W graph example." << std::endl;
+
+//[lambert_w_graph_1
+//] [/lambert_w_graph_1]
+ {
+ std::map<const double, double> wm1s; // Lambert W-1 branch values.
+ std::map<const double, double> w0s; // Lambert W0 branch values.
+
+ std::cout.precision(std::numeric_limits<double>::max_digits10);
+
+ int count = 0;
+ for (double z = -0.36787944117144232159552377016146086744581113103176804; z < 2.8; z += 0.001)
+ {
+ double w0 = lambert_w0(z);
+ w0s[z] = w0;
+ // std::cout << "z " << z << ", w = " << w0 << std::endl;
+ count++;
+ }
+ std::cout << "points " << count << std::endl;
+
+ count = 0;
+ for (double z = -0.3678794411714423215955237701614608727; z < -0.001; z += 0.001)
+ {
+ double wm1 = lambert_wm1(z);
+ wm1s[z] = wm1;
+ count++;
+ }
+ std::cout << "points " << count << std::endl;
+
+ svg_2d_plot data_plot;
+ data_plot.title("Lambert W function.")
+ .x_size(400)
+ .y_size(300)
+ .legend_on(true)
+ .legend_lines(true)
+ .x_label("z")
+ .y_label("W")
+ .x_range(-1, 3.)
+ .y_range(-4., +1.)
+ .x_major_interval(1.)
+ .y_major_interval(1.)
+ .x_major_grid_on(true)
+ .y_major_grid_on(true)
+ //.x_values_on(true)
+ //.y_values_on(true)
+ .y_values_rotation(horizontal)
+ //.plot_window_on(true)
+ .x_values_precision(3)
+ .y_values_precision(3)
+ .coord_precision(4) // Needed to avoid stepping on curves.
+ .copyright_holder("Paul A. Bristow")
+ .copyright_date("2018")
+ //.background_border_color(black);
+ ;
+ data_plot.plot(w0s, "W0 branch").line_color(red).shape(none).line_on(true).bezier_on(false).line_width(1);
+ data_plot.plot(wm1s, "W-1 branch").line_color(blue).shape(none).line_on(true).bezier_on(false).line_width(1);
+ data_plot.write("./lambert_w_graph");
+
+ show_2d_plot_settings(data_plot); // For plot diagnosis only.
+
+ } // small z Lambert W
+
+ { // bigger argument z Lambert W
+
+ std::map<const double, double> w0s_big; // Lambert W0 branch values for large z and W.
+ std::map<const double, double> wm1s_big; // Lambert W-1 branch values for small z and large -W.
+ int count = 0;
+ for (double z = -0.3678794411714423215955237701614608727; z < 10000.; z += 50.)
+ {
+ double w0 = lambert_w0(z);
+ w0s_big[z] = w0;
+ count++;
+ }
+ std::cout << "points " << count << std::endl;
+
+ count = 0;
+ for (double z = -0.3678794411714423215955237701614608727; z < -0.001; z += 0.001)
+ {
+ double wm1 = lambert_wm1(z);
+ wm1s_big[z] = wm1;
+ count++;
+ }
+ std::cout << "Lambert W0 large z argument points = " << count << std::endl;
+
+ svg_2d_plot data_plot2;
+ data_plot2.title("Lambert W0 function for larger z.")
+ .x_size(400)
+ .y_size(300)
+ .legend_on(false)
+ .x_label("z")
+ .y_label("W")
+ //.x_label_on(true)
+ //.y_label_on(true)
+ //.xy_values_on(false)
+ .x_range(-1, 10000.)
+ .y_range(-1., +8.)
+ .x_major_interval(2000.)
+ .y_major_interval(1.)
+ .x_major_grid_on(true)
+ .y_major_grid_on(true)
+ //.x_values_on(true)
+ //.y_values_on(true)
+ .y_values_rotation(horizontal)
+ //.plot_window_on(true)
+ .x_values_precision(3)
+ .y_values_precision(3)
+ .coord_precision(4) // Needed to avoid stepping on curves.
+ .copyright_holder("Paul A. Bristow")
+ .copyright_date("2018")
+ //.background_border_color(black);
+ ;
+
+ data_plot2.plot(w0s_big, "W0 branch").line_color(red).shape(none).line_on(true).bezier_on(false).line_width(1);
+ // data_plot2.plot(wm1s_big, "W-1 branch").line_color(blue).shape(none).line_on(true).bezier_on(false).line_width(1);
+ // This wouldn't show anything useful.
+ data_plot2.write("./lambert_w_graph_big_w");
+ } // Big argument z Lambert W
+
+ { // Lambert W0 Derivative plots
+
+ // std::map<const double, double> wm1ps; // Lambert W-1 prime branch values.
+ std::map<const double, double> w0ps; // Lambert W0 prime branch values.
+
+ std::cout.precision(std::numeric_limits<double>::max_digits10);
+
+ int count = 0;
+ for (double z = -0.36; z < 3.; z += 0.001)
+ {
+ double w0p = lambert_w0_prime(z);
+ w0ps[z] = w0p;
+ // std::cout << "z " << z << ", w0 = " << w0 << std::endl;
+ count++;
+ }
+ std::cout << "points " << count << std::endl;
+
+ //count = 0;
+ //for (double z = -0.36; z < -0.1; z += 0.001)
+ //{
+ // double wm1p = lambert_wm1_prime(z);
+ // std::cout << "z " << z << ", w-1 = " << wm1p << std::endl;
+ // wm1ps[z] = wm1p;
+ // count++;
+ //}
+ //std::cout << "points " << count << std::endl;
+
+ svg_2d_plot data_plotp;
+ data_plotp.title("Lambert W0 prime function.")
+ .x_size(400)
+ .y_size(300)
+ .legend_on(false)
+ .x_label("z")
+ .y_label("W0'")
+ .x_range(-0.3, +1.)
+ .y_range(0., +5.)
+ .x_major_interval(0.2)
+ .y_major_interval(2.)
+ .x_major_grid_on(true)
+ .y_major_grid_on(true)
+ .y_values_rotation(horizontal)
+ .x_values_precision(3)
+ .y_values_precision(3)
+ .coord_precision(4) // Needed to avoid stepping on curves.
+ .copyright_holder("Paul A. Bristow")
+ .copyright_date("2018")
+ ;
+
+ // derivative of N[productlog(0, x), 55] at x=0 to 10
+ // Plot[D[N[ProductLog[0, x], 55], x], {x, 0, 10}]
+ // Plot[ProductLog[x]/(x + x ProductLog[x]), {x, 0, 10}]
+ data_plotp.plot(w0ps, "W0 prime branch").line_color(red).shape(none).line_on(true).bezier_on(false).line_width(1);
+ data_plotp.write("./lambert_w0_prime_graph");
+ } // Lambert W0 Derivative plots
+
+ { // Lambert Wm1 Derivative plots
+
+ std::map<const double, double> wm1ps; // Lambert W-1 prime branch values.
+
+ std::cout.precision(std::numeric_limits<double>::max_digits10);
+
+ int count = 0;
+ for (double z = -0.3678; z < -0.00001; z += 0.001)
+ {
+ double wm1p = lambert_wm1_prime(z);
+ // std::cout << "z " << z << ", w-1 = " << wm1p << std::endl;
+ wm1ps[z] = wm1p;
+ count++;
+ }
+ std::cout << "Lambert W-1 prime points = " << count << std::endl;
+
+ svg_2d_plot data_plotp;
+ data_plotp.title("Lambert W-1 prime function.")
+ .x_size(400)
+ .y_size(300)
+ .legend_on(false)
+ .x_label("z")
+ .y_label("W-1'")
+ .x_range(-0.4, +0.01)
+ .x_major_interval(0.1)
+ .y_range(-20., -5.)
+ .y_major_interval(5.)
+ .x_major_grid_on(true)
+ .y_major_grid_on(true)
+ .y_values_rotation(horizontal)
+ .x_values_precision(3)
+ .y_values_precision(3)
+ .coord_precision(4) // Needed to avoid stepping on curves.
+ .copyright_holder("Paul A. Bristow")
+ .copyright_date("2018")
+ ;
+
+ // derivative of N[productlog(0, x), 55] at x=0 to 10
+ // Plot[D[N[ProductLog[0, x], 55], x], {x, 0, 10}]
+ // Plot[ProductLog[x]/(x + x ProductLog[x]), {x, 0, 10}]
+ data_plotp.plot(wm1ps, "W-1 prime branch").line_color(blue).shape(none).line_on(true).bezier_on(false).line_width(1);
+ data_plotp.write("./lambert_wm1_prime_graph");
+ } // Lambert W-1 prime graph
+ } // try
+ catch (std::exception& ex)
+ {
+ std::cout << ex.what() << std::endl;
+ }
+} // int main()
+
+ /*
+
+ //[lambert_w_graph_1_output
+
+ //] [/lambert_w_graph_1_output]
+ */