lonelyrex
2009-07-01, 08:03
各位高手大家好, 我现在用ODE45来解这个微分方程,解出来以后想设置在X(1)+X(3)=0的时候,停止,我现在在尝试使用ODESET=OPTIONS,但是始终有一个错误不明白什么意思 肯定各位高手指教
解方程
function dx=step9(t,x)
a=0.5
b=0.5
l=a+b
mh=10
m=5
g=9.81
dx=zeros(4,1)
dx(1)=x(2);
dx(2)=-1/b*(-l^3*mh*sin(-x(3)+x(1))*x(4)^2+l^2*mh*g*sin(x(1))-l^3*m*sin(-x(3)+x(1))*x(4)^2+l^2*m*g*sin(x(1))-m*a^2*l*sin(-x(3)+x(1))*x(4)^2+m*a^2*g*sin(x(1))+l^2*cos(-x(3)+x(1))*m*b*sin(-x(3)+x(1))*x(2)^2-l^2*cos(-x(3)+x(1))*g*sin(x(3))*mh-l*cos(-x(3)+x(1))*g*sin(x(3))*m*a-l^2*cos(-x(3)+x(1))*g*sin(x(3))*m)/(l^2*mh+l^2*m+m*a^2-m*l^2*cos(-x(3)+x(1))^2);
dx(3)=x(4);
dx(4)=(l^2*cos(-x(3)+x(1))*m*sin(-x(3)+x(1))*x(4)^2-l*cos(-x(3)+x(1))*m*g*sin(x(1))-m*l*b*sin(-x(3)+x(1))*x(2)^2+g*sin(x(3))*mh*l+g*sin(x(3))*m*a+g*sin(x(3))*m*l)/(l^2*mh+l^2*m+m*a^2-m*l^2*cos(-x(3)+x(1))^2);
现在做的ODESET
function [value,isterminal,direction]=event1(t,x)
theta_ns=x(1)
theta_s=x(3)
value(1)=theta_ns+theta_s
if theta_ns+theta_s=0
isterminal(1)=1
else
isterminal(1)=0
end
direction(1)=-1
运行指令:
options=odeset('event',@event1)
t0=0;
tf=1;
x0=[-0.33;-0.25;0.22;-1]
[t,x]=ode45('step9',[t0 tf],x0,options)
plot(t,x)
错误
??? Function 'lower' is not defined for values of class 'function_handle'.
Error in ==> lower at 26
[varargout{1:nargout}] = builtin('lower', varargin{:});
Error in ==> funfun\private\odeevents at 32
switch lower(eventFcn)
Error in ==> ode45 at 209
[haveEventFcn,eventFcn,eventArgs,valt,teout,yeout,ieout] = ...
希望各位指教
解方程
function dx=step9(t,x)
a=0.5
b=0.5
l=a+b
mh=10
m=5
g=9.81
dx=zeros(4,1)
dx(1)=x(2);
dx(2)=-1/b*(-l^3*mh*sin(-x(3)+x(1))*x(4)^2+l^2*mh*g*sin(x(1))-l^3*m*sin(-x(3)+x(1))*x(4)^2+l^2*m*g*sin(x(1))-m*a^2*l*sin(-x(3)+x(1))*x(4)^2+m*a^2*g*sin(x(1))+l^2*cos(-x(3)+x(1))*m*b*sin(-x(3)+x(1))*x(2)^2-l^2*cos(-x(3)+x(1))*g*sin(x(3))*mh-l*cos(-x(3)+x(1))*g*sin(x(3))*m*a-l^2*cos(-x(3)+x(1))*g*sin(x(3))*m)/(l^2*mh+l^2*m+m*a^2-m*l^2*cos(-x(3)+x(1))^2);
dx(3)=x(4);
dx(4)=(l^2*cos(-x(3)+x(1))*m*sin(-x(3)+x(1))*x(4)^2-l*cos(-x(3)+x(1))*m*g*sin(x(1))-m*l*b*sin(-x(3)+x(1))*x(2)^2+g*sin(x(3))*mh*l+g*sin(x(3))*m*a+g*sin(x(3))*m*l)/(l^2*mh+l^2*m+m*a^2-m*l^2*cos(-x(3)+x(1))^2);
现在做的ODESET
function [value,isterminal,direction]=event1(t,x)
theta_ns=x(1)
theta_s=x(3)
value(1)=theta_ns+theta_s
if theta_ns+theta_s=0
isterminal(1)=1
else
isterminal(1)=0
end
direction(1)=-1
运行指令:
options=odeset('event',@event1)
t0=0;
tf=1;
x0=[-0.33;-0.25;0.22;-1]
[t,x]=ode45('step9',[t0 tf],x0,options)
plot(t,x)
错误
??? Function 'lower' is not defined for values of class 'function_handle'.
Error in ==> lower at 26
[varargout{1:nargout}] = builtin('lower', varargin{:});
Error in ==> funfun\private\odeevents at 32
switch lower(eventFcn)
Error in ==> ode45 at 209
[haveEventFcn,eventFcn,eventArgs,valt,teout,yeout,ieout] = ...
希望各位指教