作者ANUBISANKH (Pourquoi？)
看板NTUNL
標題[爆炸] 昨天講的 bifurcation matlab file
時間Sat Sep 30 20:04:53 2006
(1) 先開一個 .m file 建立 function (他會直接要求你存成 hysterisis.m):
function dydt=hysterisis(t,x,u)
global u;
dydt=[u*x+x^3-x^5];
(2) 建立執行檔，一樣開一個 .m file:
clear all;
global u;
for i=1:100
% setting the range of parameter "u"
u=0.01*(i-50);
% different initial conditions
x0=[2.15];
y0=[0.04];
a0=[-2.15];
b0=[-0.04];
% solving odes by ode45
[t,x]=ode45(@hysterisis,0:0.1:10,x0);
[t,y]=ode45(@hysterisis,0:0.1:10,y0);
[t,a]=ode45(@hysterisis,0:0.1:10,a0);
[t,b]=ode45(@hysterisis,0:0.1:10,b0);
% defining the 100th step calculation of x as x*
X(i)=x(100);
Y(i)=y(100);
A(i)=a(100);
B(i)=b(100);
% redefining the parameter "u" as "u(i)"
U(i)=u;
end
subplot(2,2,1),plot(U,X)
ylabel('x*')
xlabel('u')
subplot(2,2,2),plot(U,Y)
ylabel('x*')
xlabel('u')
subplot(2,2,3),plot(U,A)
ylabel('x*')
xlabel('u')
subplot(2,2,4),plot(U,B)
ylabel('x*')
xlabel('u')
--
先這樣啦，試試看就好。
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