Ode.h

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/*
===========================================================================

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Copyright (C) 1999-2011 id Software LLC, a ZeniMax Media company. 

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*/

#ifndef __MATH_ODE_H__
#define __MATH_ODE_H__

/*
===============================================================================

        Numerical solvers for ordinary differential equations.

===============================================================================
*/


//===============================================================
//
//      idODE
//
//===============================================================

typedef void (*deriveFunction_t)( const float t, const void *userData, const float *state, float *derivatives );

class idODE {

public:
        virtual                         ~idODE( void ) {}

        virtual float           Evaluate( const float *state, float *newState, float t0, float t1 ) = 0;

protected:
        int                                     dimension;              // dimension in floats allocated for
        deriveFunction_t        derive;                 // derive function
        const void *            userData;               // client data
};

//===============================================================
//
//      idODE_Euler
//
//===============================================================

class idODE_Euler : public idODE {

public:
                                                idODE_Euler( const int dim, const deriveFunction_t dr, const void *ud );
        virtual                         ~idODE_Euler( void );

        virtual float           Evaluate( const float *state, float *newState, float t0, float t1 );

protected:
        float *                         derivatives;    // space to store derivatives
};

//===============================================================
//
//      idODE_Midpoint
//
//===============================================================

class idODE_Midpoint : public idODE {

public:
                                                idODE_Midpoint( const int dim, const deriveFunction_t dr, const void *ud );
        virtual                         ~idODE_Midpoint( void );

        virtual float           Evaluate( const float *state, float *newState, float t0, float t1 );

protected:
        float *                         tmpState;
        float *                         derivatives;    // space to store derivatives
};

//===============================================================
//
//      idODE_RK4
//
//===============================================================

class idODE_RK4 : public idODE {

public:
                                                idODE_RK4( const int dim, const deriveFunction_t dr, const void *ud );
        virtual                         ~idODE_RK4( void );

        virtual float           Evaluate( const float *state, float *newState, float t0, float t1 );

protected:
        float *                         tmpState;
        float *                         d1;                             // derivatives
        float *                         d2;
        float *                         d3;
        float *                         d4;
};

//===============================================================
//
//      idODE_RK4Adaptive
//
//===============================================================

class idODE_RK4Adaptive : public idODE {

public:
                                                idODE_RK4Adaptive( const int dim, const deriveFunction_t dr, const void *ud );
        virtual                         ~idODE_RK4Adaptive( void );

        virtual float           Evaluate( const float *state, float *newState, float t0, float t1 );
        void                            SetMaxError( const float err );

protected:
        float                           maxError;               // maximum allowed error
        float *                         tmpState;
        float *                         d1;                             // derivatives
        float *                         d1half;
        float *                         d2;
        float *                         d3;
        float *                         d4;
};

#endif /* !__MATH_ODE_H__ */