| 1 | #include <math.h> |
| 2 | #define NRANSI |
| 3 | #include "nrutil.h" |
| 4 | #define ITMAX 100 |
| 5 | #define EPS 3.0e-8 |
| 6 | |
| 7 | double zbrent(double (*func)(double), double x1, double x2, double tol) |
| 8 | { |
| 9 | int iter; |
| 10 | double a=x1,b=x2,c=x2,d,e,min1,min2; |
| 11 | double fa=(*func)(a),fb=(*func)(b),fc,p,q,r,s,tol1,xm; |
| 12 | |
| 13 | if ((fa > 0.0 && fb > 0.0) || (fa < 0.0 && fb < 0.0)) |
| 14 | nrerror("Root must be bracketed in zbrent"); |
| 15 | fc=fb; |
| 16 | for (iter=1;iter<=ITMAX;iter++) { |
| 1 | Loop condition is true. Entering loop body | |
|
| 17 | if ((fb > 0.0 && fc > 0.0) || (fb < 0.0 && fc < 0.0)) { |
| 18 | c=a; |
| 19 | fc=fa; |
| 20 | e=d=b-a; |
| 21 | } |
| 22 | if (fabs(fc) < fabs(fb)) { |
| |
| 23 | a=b; |
| 24 | b=c; |
| 25 | c=a; |
| 26 | fa=fb; |
| 27 | fb=fc; |
| 28 | fc=fa; |
| 29 | } |
| 30 | tol1=2.0*EPS*fabs(b)+0.5*tol; |
| 31 | xm=0.5*(c-b); |
| 32 | if (fabs(xm) <= tol1 || fb == 0.0) return b; |
| |
| 33 | if (fabs(e) >= tol1 && fabs(fa) > fabs(fb)) { |
| 4 | | Function call argument is an uninitialized value |
|
| 34 | s=fb/fa; |
| 35 | if (a == c) { |
| 36 | p=2.0*xm*s; |
| 37 | q=1.0-s; |
| 38 | } else { |
| 39 | q=fa/fc; |
| 40 | r=fb/fc; |
| 41 | p=s*(2.0*xm*q*(q-r)-(b-a)*(r-1.0)); |
| 42 | q=(q-1.0)*(r-1.0)*(s-1.0); |
| 43 | } |
| 44 | if (p > 0.0) q = -q; |
| 45 | p=fabs(p); |
| 46 | min1=3.0*xm*q-fabs(tol1*q); |
| 47 | min2=fabs(e*q); |
| 48 | if (2.0*p < (min1 < min2 ? min1 : min2)) { |
| 49 | e=d; |
| 50 | d=p/q; |
| 51 | } else { |
| 52 | d=xm; |
| 53 | e=d; |
| 54 | } |
| 55 | } else { |
| 56 | d=xm; |
| 57 | e=d; |
| 58 | } |
| 59 | a=b; |
| 60 | fa=fb; |
| 61 | if (fabs(d) > tol1) |
| 62 | b += d; |
| 63 | else |
| 64 | b += SIGN(tol1,xm)((xm) >= 0.0 ? fabs(tol1) : -fabs(tol1)); |
| 65 | fb=(*func)(b); |
| 66 | } |
| 67 | nrerror("Maximum number of iterations exceeded in zbrent"); |
| 68 | return 0.0; |
| 69 | } |
| 70 | #undef ITMAX |
| 71 | #undef EPS |
| 72 | #undef NRANSI |