#include <math.h>#define NRANSI#include "nrutil.h"#define MAXSTP 10000#define TINY 1.0e-30extern int kmax,kount;extern float *xp,**yp,dxsav;void odeint(float ystart[], int nvar, float x1, float x2, float eps, float h1,	float hmin, int *nok, int *nbad,	void (*derivs)(float, float [], float []),	void (*rkqs)(float [], float [], int, float *, float, float, float [],	float *, float *, void (*)(float, float [], float []))){	int nstp,i;	float xsav,x,hnext,hdid,h;	float *yscal,*y,*dydx;	yscal=vector(1,nvar);	y=vector(1,nvar);	dydx=vector(1,nvar);	x=x1;	h=SIGN(h1,x2-x1);	*nok = (*nbad) = kount = 0;	for (i=1;i<=nvar;i++) y[i]=ystart[i];	if (kmax > 0) xsav=x-dxsav*2.0;	for (nstp=1;nstp<=MAXSTP;nstp++) {		(*derivs)(x,y,dydx);		for (i=1;i<=nvar;i++)			yscal[i]=fabs(y[i])+fabs(dydx[i]*h)+TINY;		if (kmax > 0 && kount < kmax-1 && fabs(x-xsav) > fabs(dxsav)) {			xp[++kount]=x;			for (i=1;i<=nvar;i++) yp[i][kount]=y[i];			xsav=x;		}		if ((x+h-x2)*(x+h-x1) > 0.0) h=x2-x;		(*rkqs)(y,dydx,nvar,&x,h,eps,yscal,&hdid,&hnext,derivs);		if (hdid == h) ++(*nok); else ++(*nbad);		if ((x-x2)*(x2-x1) >= 0.0) {			for (i=1;i<=nvar;i++) ystart[i]=y[i];			if (kmax) {				xp[++kount]=x;				for (i=1;i<=nvar;i++) yp[i][kount]=y[i];			}			free_vector(dydx,1,nvar);			free_vector(y,1,nvar);			free_vector(yscal,1,nvar);			return;		}		if (fabs(hnext) <= hmin) nrerror("Step size too small in odeint");		h=hnext;	}	nrerror("Too many steps in routine odeint");}#undef MAXSTP#undef TINY#undef NRANSI