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00001 // Copyright (C) 2003 Johan Jansson. 00002 // Licensed under the GNU GPL Version 2. 00003 00004 #ifndef __WAVE_H 00005 #define __WAVE_H 00006 00007 #include <dolfin/PDE.h> 00008 00009 namespace dolfin { 00010 00011 class Wave : public PDE { 00012 public: 00013 00014 Wave(Function& source, 00015 Function& uprevious, 00016 Function& wprevious) : PDE(2) 00017 { 00018 add(f, source); 00019 add(up, uprevious); 00020 add(wp, wprevious); 00021 } 00022 00023 real lhs(const ShapeFunction& u, const ShapeFunction& v) 00024 { 00025 /* 00026 // dG(0) in time 00027 00028 return (u*v + k * k * 00029 (grad(u), grad(v))) * dx; 00030 */ 00031 00033 // cG(1) in time 00034 00035 return 00036 (2 / k * u * v + k / 2 * (grad(u), grad(v))) * dx; 00037 //(2 / k * u * v + k / 2 * (u.ddx() * v.ddx() + u.ddy() * v.ddy())) * dx; 00038 //*/ 00039 } 00040 00041 real rhs(const ShapeFunction& v) 00042 { 00043 /* 00044 // dG(0) in time 00045 00046 return (k * k * f * v + k * wp * v + up * v) * dx; 00047 */ 00048 00050 // cG(1) in time 00051 00052 return 00053 (k * f * v + 00054 2 / k * up * v - 00055 //k / 2 * (up.ddx() * v.ddx() + up.ddy() * v.ddy()) + 00056 k / 2 * (grad(up), grad(v)) + 00057 2 * wp * v) * dx; 00058 //*/ 00059 } 00060 00061 private: 00062 00063 ElementFunction f; // Source term 00064 ElementFunction up; // Position value at left end-point 00065 ElementFunction wp; // Velocity value at left end-point 00066 00067 }; 00068 00069 } 00070 00071 #endif
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