diff options
author | Samuel Niederer <43746162+samnied@users.noreply.github.com> | 2022-07-24 12:17:00 +0200 |
---|---|---|
committer | GitHub <noreply@github.com> | 2022-07-24 12:17:00 +0200 |
commit | efe7c35759afb5cbae3c1683873c5159be0be09f (patch) | |
tree | 84f2e8510132352f9943bddc577ccf32cd46f2dc /buch/chapters/110-elliptisch/images/lemnispara.cpp | |
parent | add current work (diff) | |
parent | Merge pull request #26 from p1mueller/master (diff) | |
download | SeminarSpezielleFunktionen-efe7c35759afb5cbae3c1683873c5159be0be09f.tar.gz SeminarSpezielleFunktionen-efe7c35759afb5cbae3c1683873c5159be0be09f.zip |
Merge branch 'AndreasFMueller:master' into master
Diffstat (limited to 'buch/chapters/110-elliptisch/images/lemnispara.cpp')
-rw-r--r-- | buch/chapters/110-elliptisch/images/lemnispara.cpp | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/buch/chapters/110-elliptisch/images/lemnispara.cpp b/buch/chapters/110-elliptisch/images/lemnispara.cpp new file mode 100644 index 0000000..6f4d55d --- /dev/null +++ b/buch/chapters/110-elliptisch/images/lemnispara.cpp @@ -0,0 +1,126 @@ +/* + * lemnispara.cpp -- Display parametrisation of the lemniskate + * + * (c) 2022 Prof Dr Andreas Müller, OST Ostschweizer Fachhochschule + */ +#include <cstdio> +#include <cstdlib> +#include <cmath> +#include <gsl/gsl_sf_elljac.h> +#include <iostream> +#include <fstream> +#include <map> +#include <string.h> +#include <string> + +const static double s = sqrt(2); +const static double k = 1 / s; +const static double m = k * k; + +typedef std::pair<double, double> point_t; + +point_t operator*(const point_t& p, double s) { + return point_t(s * p.first, s * p.second); +} + +static double norm(const point_t& p) { + return hypot(p.first, p.second); +} + +static point_t normalize(const point_t& p) { + return p * (1/norm(p)); +} + +static point_t normal(const point_t& p) { + return std::make_pair(p.second, -p.first); +} + +class lemniscate : public point_t { + double sn, cn, dn; +public: + lemniscate(double t) { + gsl_sf_elljac_e(t, m, &sn, &cn, &dn); + first = s * cn * dn; + second = cn * sn; + } + point_t tangent() const { + return std::make_pair(-s * sn * (1.5 - sn * sn), + dn * (1 - 2 * sn * sn)); + } + point_t unittangent() const { + return normalize(tangent()); + } + point_t normal() const { + return ::normal(tangent()); + } + point_t unitnormal() const { + return ::normal(unittangent()); + } +}; + +std::ostream& operator<<(std::ostream& out, const point_t& p) { + char b[1024]; + snprintf(b, sizeof(b), "({%.4f*\\dx},{%.4f*\\dy})", p.first, p.second); + out << b; + return out; +} + +int main(int argc, char *argv[]) { + std::ofstream out("lemnisparadata.tex"); + + // the curve + double tstep = 0.01; + double tmax = 4.05; + out << "\\def\\lemnispath{ "; + out << lemniscate(0); + for (double t = tstep; t < tmax; t += tstep) { + out << std::endl << "\t" << "-- " << lemniscate(t); + } + out << std::endl; + out << "}" << std::endl; + + out << "\\def\\lemnispathmore{ "; + out << lemniscate(tmax); + double tmax2 = 7.5; + for (double t = tmax + tstep; t < tmax2; t += tstep) { + out << std::endl << "\t" << "-- " << lemniscate(t); + } + out << std::endl; + out << "}" << std::endl; + + // individual points + tstep = 0.2; + int i = 0; + char name[3]; + strcpy(name, "L0"); + for (double t = 0; t <= tmax; t += tstep) { + char c = 'A' + i++; + char buffer[128]; + lemniscate l(t); + name[0] = 'L'; + name[1] = c; + out << "\\coordinate (" << name << ") at "; + out << l << ";" << std::endl; + name[0] = 'T'; + out << "\\coordinate (" << name << ") at "; + out << l.unittangent() << ";" << std::endl; + name[0] = 'N'; + out << "\\coordinate (" << name << ") at "; + out << l.unitnormal() << ";" << std::endl; + name[0] = 'C'; + out << "\\def\\" << name << "{ "; + out << "\\node[color=red] at ($(L" << c << ")+0.06*(N" << c << ")$) "; + out << "[rotate={"; + double w = 180 * atan2(l.unitnormal().second, + l.unitnormal().first) / M_PI; + snprintf(buffer, sizeof(buffer), "%.1f", w); + out << buffer; + out << "-90}]"; + snprintf(buffer, sizeof(buffer), "%.1f", t); + out << " {$\\scriptstyle " << buffer << "$};" << std::endl; + out << "}" << std::endl; + } + + out.close(); + return EXIT_SUCCESS; +} |