q412.m

来自「电路与系统专业的matlab程序。有很多经典的实例。」· M 代码 · 共 18 行

% 求极值
fn=' 2*exp(-x)*sin(x) ';	%  define function for min

ezplot 2*exp(-x)*sin(x),grid on
xmin=fminbnd(fn ,-4,2 )	%  search over range 2<x<5
x=xmin;	%  
ymin=eval(fn,x) 	%  evaluate at xmin
hold on
plot(xmin,ymin,'o')
fx=' -2*exp(-x)*sin(x) ';	%  define for max:note minus sign
figure(2)
ezplot -2*exp(-x)*sin(x),grid on
xmax=fminbnd(fx ,-3,-1)	%  search over range 0<x<3
x=xmax;	%  
ymax=eval(fx)	%  evaluate at xmax
hold on
plot(xmax,ymax,'*')