stiff.h

#ifndef STIFF_HINCLUDED
#define STIFF_HINCLUDED

typedef struct StiffContextStructure {
    double epsmin;      /* relative accuracy criterion */
    double sqreps;      /* parameter to calculate initial timestep */
    double epscl;       /* 1/epsmin */
    double epsmax;      /* repeat timestep if correction is
                   greater than epsmax*epsmin*y(i) */   
    double dtmin;       /* minimum timestep allowed */
    int itermax;        /* number of corrector iterations */
    int nv;             /* number of dependent variables */
    double *ymin;       /* minimum value for y */
    double *y0;         /* initial y for global timestep */
    double *y1;         /* predicted value */
    double *q;          /* scratch for creation rate */
    double *d;          /* scratch for destruction rate */
    double *rtau;       /* ratio of timestep to timescale */
    double *ys;         /* initial y for individual timesteps */
    double *qs;         /* initial production rate */
    double *rtaus;      /* initial rtau */
    double *scrarray;
    void *Data; /* Pointer to fixed data used by derivs */
    void (*derivs)(double, const double [], double [], double [], void *Data);
} STIFF;

/*
 * Integrator Step Headers
 */

STIFF *StiffInit(double eps,    /* relative accuracy parameter */
         int nv,    /* number of dependent variables */
         void *Data,    /* pointer to extra data */
         void (*derivs)(double t, const double yin[],  /* input */
                double yheat[], /* heating or creation
                           rate */
                   double ycool[],  /* cooling or
                           destruction rate */
                void *Data)
         );
           
void StiffFinalize( STIFF *s );
void StiffStep(STIFF *s, double y[], double tstart, double htry) ;
void StiffSetYMin(STIFF *s, const double *ymin);

#ifndef TESTCHEMEQ
/* 
 * Root Finder Header
 */

double RootFind(double (*func)(void *Data, double), void *Data,
        double x1, double x2, double tol);

#endif
#endif