#include <math.h>#define JMAX 40float rtbis(float (*func)(float), float x1, float x2, float xacc){	void nrerror(char error_text[]);	int j;	float dx,f,fmid,xmid,rtb;	f=(*func)(x1);	fmid=(*func)(x2);	if (f*fmid >= 0.0) nrerror("Root must be bracketed for bisection in rtbis");	rtb = f < 0.0 ? (dx=x2-x1,x1) : (dx=x1-x2,x2);	for (j=1;j<=JMAX;j++) {		fmid=(*func)(xmid=rtb+(dx *= 0.5));		if (fmid <= 0.0) rtb=xmid;		if (fabs(dx) < xacc || fmid == 0.0) return rtb;	}	nrerror("Too many bisections in rtbis");	return 0.0;}#undef JMAX