From ae956bffbf796005e1f59a9c430cef69e21e13f6 Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@gmail.com>
Date: Wed, 6 Oct 2010 23:42:05 -0400
Subject: Add RKF45 method.

---
 tests/Makefile.am |  4 +++-
 tests/RKF45.cpp   | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)
 create mode 100644 tests/RKF45.cpp

(limited to 'tests')

diff --git a/tests/Makefile.am b/tests/Makefile.am
index cab6d98..f6ad25e 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -24,7 +24,8 @@ check_PROGRAMS = Euler-test                                                    \
                  Heun-test                                                     \
                  RK4-test                                                      \
                  HE12-test                                                     \
-                 BS23-test
+                 BS23-test                                                     \
+                 RKF45-test
 TESTS          = $(check_PROGRAMS)
 
 Euler_test_SOURCES    = Euler.cpp
@@ -33,3 +34,4 @@ Heun_test_SOURCES     = Heun.cpp
 RK4_test_SOURCES      = RK4.cpp
 HE12_test_SOURCES     = HE12.cpp
 BS23_test_SOURCES     = BS23.cpp
+RKF45_test_SOURCES    = RKF45.cpp
diff --git a/tests/RKF45.cpp b/tests/RKF45.cpp
new file mode 100644
index 0000000..8b87216
--- /dev/null
+++ b/tests/RKF45.cpp
@@ -0,0 +1,39 @@
+#include "vZ.hpp"
+#include <cmath>
+#include <cstdlib>
+#include <iostream>
+#include <iomanip>
+
+// y' = y (y == C*exp(t))
+double
+f(double t, double y)
+{
+  return y;
+}
+
+int
+main()
+{
+  vZ::RKF45Integrator integrator(f);
+  integrator.tol(1e-6).y(1.0).x(0.0).h(0.06);
+
+  integrator.integrate(2.0);
+
+  double actual   = integrator.y();
+  double expected = std::exp(2.0);
+
+  std::cout << std::setprecision(10)
+            << "Numerical:  " << actual << std::endl
+            << "Expected:   " << expected  << std::endl
+            << "h:          " << integrator.h() << std::endl
+            << "rejections: " << integrator.rejections() << std::endl;
+
+  double error = std::fabs(expected - actual)/expected;
+  if (error > 1.5e-6) {
+    std::cerr << "Error:      " << 100.0*error << "%" << std::endl;
+    return EXIT_FAILURE;
+  } else {
+    std::cout << "Error:      " << 100.0*error << "%" << std::endl;
+    return EXIT_SUCCESS;
+  }
+}
-- 
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