无约束一维极值问题matlab代码

function [x,minf] = minGS(f,XMAX,sigma1,sigma2,alpha,eps) format long; if nargin == 5 eps = 1.0e-6; end if sigma1<=0 || sigma1>1 disp('sigma1参数不对！'); x = NaN; minf = NaN; return; else if sigma2 <= sigma1 disp('sigma2参数不对！'); x = NaN; minf = NaN; return; else if alpha <= 1 disp('alpha参数不对！'); x = NaN; minf = NaN; return; end end end df = diff(f); f0 = subs(f, findsym(f),0); df0 = subs(df, findsym(df),0); a = 0; b = XMAX; k = 0; t = (a+b)/2; while 1 ft = subs(f,findsym(f),t); f1 = f0 + sigma1*t*df0; if ft <= f1 f2 = f0 + sigma2*t*df0; if ft >= f2 x = t; break; else a = t; if b < XMAX t = (a+b)/2; else t = alpha*t; end end else b = t; t = (a+b)/2; end k = k+1; end minf = subs(f,findsym(f),x); format short;