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authorTavian Barnes <tavianator@gmail.com>2010-10-06 20:44:32 -0400
committerTavian Barnes <tavianator@gmail.com>2010-10-06 20:44:32 -0400
commitd5639168232d1c111d6924b10c6abd74204abec1 (patch)
tree225caf58d60a885f2283b8e1eb0a220f6a2ab772 /src/vZ
parentbc0b87a5cb49cda5f79f1f1374c33a26725d2dde (diff)
downloadvz-d5639168232d1c111d6924b10c6abd74204abec1.tar.xz
Add Heun's method.
Diffstat (limited to 'src/vZ')
-rw-r--r--src/vZ/Heun.hpp95
-rw-r--r--src/vZ/Integrator.hpp1
2 files changed, 95 insertions, 1 deletions
diff --git a/src/vZ/Heun.hpp b/src/vZ/Heun.hpp
new file mode 100644
index 0000000..b70df9e
--- /dev/null
+++ b/src/vZ/Heun.hpp
@@ -0,0 +1,95 @@
+/*************************************************************************
+ * Copyright (C) 2009-2010 Tavian Barnes <tavianator@gmail.com> *
+ * *
+ * This file is part of The vZ Library. *
+ * *
+ * The vZ Library is free software; you can redistribute it and/or *
+ * modify it under the terms of the GNU Lesser General Public License as *
+ * published by the Free Software Foundation; either version 3 of the *
+ * License, or (at your option) any later version. *
+ * *
+ * The vZ Library is distributed in the hope that it will be useful, but *
+ * WITHOUT ANY WARRANTY; without even the implied warranty of *
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
+ * Lesser General Public License for more details. *
+ * *
+ * You should have received a copy of the GNU Lesser General Public *
+ * License along with this program. If not, see *
+ * <http://www.gnu.org/licenses/>. *
+ *************************************************************************/
+
+#ifndef VZ_HEUN_HPP
+#define VZ_HEUN_HPP
+
+namespace vZ
+{
+ // Heun's method
+ //
+ // Second order Runge-Kutta method
+ // Two function evaluations per step
+ // Its tableau is:
+ //
+ // 0 |
+ // 1 | 1
+ // --+---------
+ // | 1/2 1/2
+ //
+ // k1 = dt*f(y[n])
+ // k2 = dt*f(y[n] + dt*k1)
+ // y[n + 1] = y[n] + 1/2*(k1 + k2)
+ template <typename Y>
+ class GenericHeunIntegrator : public GenericSimpleIntegrator<Y>
+ {
+ public:
+ typedef typename GenericSimpleIntegrator<Y>::Scalar Scalar;
+ typedef typename GenericSimpleIntegrator<Y>::Function Function;
+
+ GenericHeunIntegrator(Function f)
+ : GenericSimpleIntegrator<Y>(f, s_a, s_b) { }
+ ~GenericHeunIntegrator() { }
+
+ private:
+ typedef typename GenericSimpleIntegrator<Y>::ACoefficients ACoefficients;
+ typedef typename GenericSimpleIntegrator<Y>::BCoefficients BCoefficients;
+
+ static ACoefficients s_a;
+ static BCoefficients s_b;
+
+ static Scalar s_a2Arr[1];
+ static std::vector<Scalar> s_aArr[1];
+ static Scalar s_bArr[2];
+ };
+
+ // Type alias
+ typedef GenericHeunIntegrator<double> HeunIntegrator;
+
+ // Implementation
+
+ template <typename Y>
+ typename GenericHeunIntegrator<Y>::Scalar
+ GenericHeunIntegrator<Y>::s_a2Arr[1] = {
+ Scalar(1)
+ };
+
+ template <typename Y>
+ std::vector<typename GenericHeunIntegrator<Y>::Scalar>
+ GenericHeunIntegrator<Y>::s_aArr[1] = {
+ std::vector<Scalar>(s_a2Arr, s_a2Arr + 1)
+ };
+
+ template <typename Y>
+ typename GenericHeunIntegrator<Y>::ACoefficients
+ GenericHeunIntegrator<Y>::s_a(s_aArr, s_aArr + 1);
+
+ template <typename Y>
+ typename GenericHeunIntegrator<Y>::Scalar
+ GenericHeunIntegrator<Y>::s_bArr[2] = {
+ Scalar(1)/Scalar(2), Scalar(1)/Scalar(2)
+ };
+
+ template <typename Y>
+ typename GenericHeunIntegrator<Y>::BCoefficients
+ GenericHeunIntegrator<Y>::s_b(s_bArr, s_bArr + 2);
+}
+
+#endif // VZ_HEUN_HPP
diff --git a/src/vZ/Integrator.hpp b/src/vZ/Integrator.hpp
index 34bc870..9346eb8 100644
--- a/src/vZ/Integrator.hpp
+++ b/src/vZ/Integrator.hpp
@@ -82,5 +82,4 @@ namespace vZ
}
}
-
#endif // VZ_INTEGRATOR_HPP