Add base Integrator class, and simple compilation test.

2 files changed, 139 insertions, 0 deletions

diff --git a/src/vZ/integrator.hpp b/src/vZ/integrator.hpp
new file mode 100644
index 0000000..394f40f
--- /dev/null
+++ b/src/vZ/integrator.hpp
@@ -0,0 +1,83 @@
+/*************************************************************************
+ * 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_INTEGRATOR_HPP
+#define VZ_INTEGRATOR_HPP
+
+#include <tr1/functional>
+#include <algorithm>
+
+namespace vZ
+{
+  // Base Integrator class
+  //
+  // All integration methods derrive from this class
+  // If the initial value problem is specified as
+  //   y' = f(t, y); y(t0) = y0
+  // then an Integrator could be constructed as Integrator(f, dt).y(y0).t(t0)
+  template <typename Real>
+  class GenericIntegrator
+  {
+  public:
+    typedef std::tr1::function<Real (Real, Real)> Function;
+
+    // By default, y and t start at zero
+    GenericIntegrator(Function f, Real dt)
+      : m_f(f), m_y(0), m_t(0), m_dt(dt) { }
+    virtual ~GenericIntegrator() { }
+
+    GenericIntegrator& y(Real y)   { m_y  = y;  return *this; }
+    GenericIntegrator& t(Real t)   { m_t  = t;  return *this; }
+    GenericIntegrator& dt(Real dt) { m_dt = dt; return *this; }
+
+    Real y()  const { return m_y; }
+    Real t()  const { return m_t; }
+    Real dt() const { return m_dt; }
+
+    // Integrate until time t
+    void integrate(Real t_final);
+
+  protected:
+    virtual void step(Real& t, Real& dt) = 0;
+    Function m_f;
+
+  private:
+    Real m_y;
+    Real m_t, m_dt;
+  };
+
+  // Type alias
+  typedef GenericIntegrator<double> Integrator;
+
+  // Definitions
+
+  template <typename Real>
+  void
+  GenericIntegrator<Real>::integrate(Real t_final)
+  {
+    while (m_t < t_final) {
+      m_dt = std::min(m_dt, t_final - m_t);
+      step(m_t, m_dt);
+    }
+  }
+}
+
+
+#endif // VZ_INTEGRATOR_HPP
diff --git a/src/vZ/simple.hpp b/src/vZ/simple.hpp
new file mode 100644
index 0000000..65b7560
--- /dev/null
+++ b/src/vZ/simple.hpp
@@ -0,0 +1,56 @@
+/*************************************************************************
+ * 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_SIMPLE_HPP
+#define VZ_SIMPLE_HPP
+
+#include <vector>
+
+namespace vZ
+{
+  // Base class for non-adaptive RK-style algorithms
+  template <typename Real>
+  class GenericSimpleIntegrator : public GenericIntegrator<Real>
+  {
+  public:
+    typedef typename GenericIntegrator<Real>::Function Function;
+
+    // Coefficients in the tableau representation of the RK algorithm
+    typedef std::vector<std::vector<Real> > ACoefficients;
+    typedef std::vector<Real>               BCoefficients;
+
+    GenericSimpleIntegrator(Function f, Real dt,
+                            ACoefficients a, BCoefficients b)
+      : GenericIntegrator<Real>(f, dt), m_a(a), m_b(b) { }
+    virtual ~GenericSimpleIntegrator() { }
+
+  protected:
+    virtual void step(Real& t, Real& dt);
+
+  private:
+    ACoefficients m_a;
+    BCoefficients m_b;
+  };
+
+  // Type alias
+  typedef GenericSimpleIntegrator<double> SimpleIntegrator;
+}
+
+#endif // VZ_SIMPLE_HPP