From 2c2b69e1df183f118c45d74c18c7e84934aaff1f Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@gmail.com>
Date: Mon, 11 Oct 2010 02:38:46 -0400
Subject: Support systems of ODEs.

---
 tests/EquationSystem.cpp | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 tests/EquationSystem.cpp

(limited to 'tests/EquationSystem.cpp')

diff --git a/tests/EquationSystem.cpp b/tests/EquationSystem.cpp
new file mode 100644
index 0000000..973dd30
--- /dev/null
+++ b/tests/EquationSystem.cpp
@@ -0,0 +1,46 @@
+#include "vZ.hpp"
+#include <cmath>
+#include <cstdlib>
+#include <iostream>
+#include <iomanip>
+
+typedef vZ::EquationSystem<2> Y;
+
+// y'' = y (y == C*exp(t))
+Y
+f(double t, Y y)
+{
+  Y r;
+  r[0] = y[1];
+  r[1] = y[0];
+  return r;
+}
+
+int
+main()
+{
+  Y y;
+  y[0] = 1.0;
+  y[1] = 1.0;
+  vZ::GenericEulerIntegrator<Y> integrator(f);
+  integrator.y(y).x(0.0).h(0.01);
+
+  integrator.integrate(2.0);
+
+  double actual   = integrator.y()[0];
+  double expected = std::exp(2.0);
+
+  std::cout << std::setprecision(10)
+            << "Numerical:  " << actual << std::endl
+            << "Expected:   " << expected  << std::endl
+            << "Iterations: " << integrator.iterations() << std::endl;
+
+  double error = std::fabs(expected - actual)/expected;
+  if (error > 0.01) {
+    std::cerr << "Error:      " << 100.0*error << "%" << std::endl;
+    return EXIT_FAILURE;
+  } else {
+    std::cout << "Error:      " << 100.0*error << "%" << std::endl;
+    return EXIT_SUCCESS;
+  }
+}
-- 
cgit v1.2.3