About this ode function

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qingze
qingze 2014-10-15
评论： qingze 2014-10-15
I want to calculate this ode function with initial value y(4)=-3. But it shows not enough input error at line
dy= (K1*t+K2*y-az)/(K3*t+K4*y+kz); Can someone help please? Thanks!
function dy = coexistline(t,y)
K1 =4.9493e-04;
K2 =-1.0058e-04;
K3 =1.0058e-04;
K4 =0.0081;
az = 0.088235;
kz = -1.65625;
%dy = zeros(1,1); % a column vector
dy= (K1*t+K2*y-az)/(K3*t+K4*y+kz);
options = odeset('RelTol',1e-4,'AbsTol',[1e-4 1e-4 1e-5]);
[T,Y] = ode45(@coexistline,[-10 10],-3,options);
plot(T,Y,'-o')

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回答（1 个）

Stephen Carter
Stephen Carter 2014-10-15
I think 'AbsTol',[1e-4 1e-4 1e-5] is your problem. Since your solution has only one component for each timestep, I believe your tolerance also needs to be scalar. Try 'AbsTol',1e-4 instead.
And... looking further at what you said... you say you want initial value y(4)=-3. Do you mean you want y to equal -3 at t=4? If so, then your input is wrong. You seem to put y as -3 at time -10.
For additional help see http://www.mathworks.com/help/matlab/ref/ode45.html

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