Differences

This shows you the differences between two versions of the page.

--- libnum:classes:index [2026/03/04 15:24] – abc
+++ libnum:classes:index [2026/03/04 15:43] (current) – abc
@@ Line 3: / Line 3: @@
   namespace NumericMethods
-  * [[gear|Integration of Linear differential equations. Gear's method.]]
+  * [[gear|Gear Integration method]] (Integration of Systems of Linear Differential Equations).
-See: ''gear.h'' and ''gear.asst.h'' files.
-class [[#Gear|Gear]]; \\
-class [[#GearUserProc|GearUserProc]]; \\
-struct [[#GearEngineContext|GearEngineContext]]; \\
-class [[#GearEngineCallback|GearEngineCallback]]; \\
-class [[#GearAssistant|GearAssistant]]; \\
-typedef DoubleParamsMap [[#GearParams|GearParams]]; \\
-class [[#GearStatistics|GearStatistics]]; \\
-class [[#GearAllocator|GearAllocator]]; \\
-===== Gear =====
-  class Gear
-  {
-   public:
-    Gear();
-   ~Gear();
-    void set(int n, GearUserProc* derFunc, GearUserProc* jacFunc);
-    void setCallback(GearEngineCallback& f) { callback = &f;}
-    Message solve(const double t_begin, const double t_end, const double* y0);
-    GearEngineContext engineContext;
-    GearAssistant assistant;
-  };
-The 'set' method of Gear objects defines the dimension, starting Y values and functions
-to calculate the derivative function values and DY, the Jacobian.
-The Gear object has its private Allocator which provides memory to consecutive runs of
-'solve' procedure.
-The rest settings and user interactions are done via GearAssistance object, the public
-property of the Gear object. E.g. 'parameters', 'statistics'.
-===== GearUserProc =====
-The Base class of procedures to calculate //y'= ∂y/∂t// and //jacobian = Dy'/Dy//.
-May be used as the default, being the wrapper of ordinary C-functions
-//bool(*)(int n, double t, const double* y, double* result)//.
-  class GearUserProc {
-   public:
-    typedef bool(*PUDF)(int, double, const double[], double[]);
-    GearUserProc(PUDF = nullptr);
-    //virtual bool operator()(int n, double x, const double y[], double result[]);
-    virtual bool call(int n, double x, const double y[], double result[]);
-  };
-===== GearEngineContext =====
-Read-only references to member variables of the Gear object.
-  struct GearEngineContext
-  {
-   const int&    n;        // dimension
-   const int&    q;        // current degree of interpolation
-   const double& h;        // current step of integration
-   const double& t;        // current time
-   const double* const& Z; // values (ref to Z[])
-  };
-===== GearEngineCallback =====
-The hook/callback object in Gear::solve(). The Base class for user defined interfaces. Default callback does nothing. Use //GearEngineCallbackEmbed// to provide an ordinary C-function.
-  class GearEngineCallback
-  {
-   public:
-    virtual bool call(const GearEngineContext&) {
-      return true;  // return 'false' to cancel caller proc
-    }
-  };
-  class GearEngineCallbackEmbed : public GearEngineCallback
-  {
-   public:
-    typedef bool (*PCallback)(const GearEngineContext&);
-    GearEngineCallbackEmbed(PCallback = nullptr); // nullptr -- no output in solve()
-    virtual bool call(const GearEngineContext&) override;
-  };
-===== GearAssistant =====
-  class GearAssistant
-  {
-   public:
-    GearParams     params;
-    GearStatistics statistics;
-  };
-===== GearAllocator =====
-  class GearAllocator
-  {
-   public:
-    GearAllocator(Gear& owner);
-    ~GearAllocator();
-    bool allocateMemory(int task_dimension);
-  };
-===== GearParams =====
-  class DoubleParamsMap
-  {
-   public:
-    DoubleParamsMap() : params() {}
-    bool declareParameter(const char* name, double value=0);
-    bool setParameter(ParamID id, double value);  // parameter SHOULD be declared before!
-    double getParameter(ParamID id) const;
-    std::string getParameterNames() const;  // informative/debug purposes
-   private:
-    std::map<ParamID,double> params;
-  };
-//GearEngine// tuning parameters are (doubles):
-  EPS = 0.01;
-  HINI = 1e-10;
-  HMIN = 1e-18;
-  HMAX = BIG_VAL;
-  RHMAX = 1;
-See Gear Algorithm for details.