From bfd6e3d56f2e91f81b42c811fbff62abc153724d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andreas=20M=C3=BCller?= <andreas.mueller@ost.ch>
Date: Sat, 16 Oct 2021 10:09:16 +0200
Subject: new files

---
 buch/chapters/110-elliptisch/images/rechteck.cpp | 54 ++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 buch/chapters/110-elliptisch/images/rechteck.cpp

(limited to 'buch/chapters/110-elliptisch/images/rechteck.cpp')

diff --git a/buch/chapters/110-elliptisch/images/rechteck.cpp b/buch/chapters/110-elliptisch/images/rechteck.cpp
new file mode 100644
index 0000000..6bd6a06
--- /dev/null
+++ b/buch/chapters/110-elliptisch/images/rechteck.cpp
@@ -0,0 +1,54 @@
+/*
+ * rechteck.cpp
+ *
+ * (c) 2021 Prof Dr Andreas Müller, OST Ostschweizer Fachhochschule
+ */
+#include <cmath>
+#include <cstdlib>
+#include <cstdio>
+#include <complex>
+#include <iostream>
+
+double	ast = 1;
+
+std::complex<double>	integrand(double k, const std::complex<double>& z) {
+	std::complex<double>	s = z * z;
+	std::complex<double>	eins(1);
+	std::complex<double>	result = eins / sqrt((eins - s) * (eins - k * k * s));
+	return ast * ((result.imag() < 0) ? -result : result);
+}
+
+std::complex<double>	segment(double k, const std::complex<double>& z1,
+		const std::complex<double>& z2, int n = 100) {
+	std::complex<double>	dz = z2 - z1;
+	std::complex<double>	summe(0);
+	double	h = 1. / n;
+	summe = integrand(k, z1);
+	summe += integrand(k, z2);
+	for (int i = 1; i < n; i++) {
+		double	t = i * h;
+		std::complex<double>	z = (1 - t) * z1 + t * z2;
+		summe += 2. * integrand(k, z);
+	}
+	return dz * h * summe / 2.;
+}
+
+int	main(int argc, char *argv[]) {
+	double	k = 0.5;
+	double	y = -0.0001;
+	double	xstep = -0.1;
+	ast = 1;
+	std::complex<double>	z(0, y);
+	std::complex<double>	w = segment(k, std::complex<double>(0), z);
+	std::cout << z << std::endl;
+	int	counter = 100;
+	while (counter-- > 0) {
+		std::complex<double>	znext = z + std::complex<double>(xstep);
+		std::complex<double>	incr = segment(k, z, znext);
+		w += incr;
+		std::cout << znext << " -> " << w << ", ";
+		std::cout << integrand(k, znext) << std::endl;
+		z = znext;
+	}
+	return EXIT_SUCCESS;
+}
-- 
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