I’m solving a DAE using ode15i. I use the same syntaxs as the example of Robertson in Matlab help
https://it.mathworks.com/help/matlab/ref/ode15i.html?s_tid=doc_ta
The script is
h = 2/2; % h = L/n, L = 2, n = 2

y0 = [0;-2/h^2;1;2/h^2;1/h;-1/h;1/h;0];
yp0 = [
-2.0000
-0.0545
2.0000
0.0545
0
0
0
0];

%The initial conditions must be "consistent", meaning
% that f(T0,Y0,YP0)=0
% With y0 and yp0 given, Node_2(0,y0,yp0) = [0 … 0] so initial conditions
% are consistent

%opt = odeset(‘RelTol’,10^-3,’AbsTol’,10^-6,’Jacobian’,@Jac_Node_2); %Optionnal

tspan = [0 4];
[t,y] = ode15i(@Node_2,tspan,y0,yp0);%,opt);
And the odefunction is :
function res = Node_2(t,y,yp)
h = 2/2;
m = 25000*0.12^2/9.81;

res = [
(y(3) – y(1))/h – y(5);
(y(6)-y(5))/h – m*yp(2);
y(1);
yp(1) – y(2);
(y(8)-y(3))/h – y(6);
(y(7)-y(6))/h – m*yp(4);
yp(3) – y(4);
y(8)
];

end
The problem is that i get the following error :
Warning: Failure at t=0.000000e+00. Unable to meet integration tolerances without reducing the step size below the smallest value allowed (0.000000e+00) at time t.
I tried to change the relative and absolute error tolerance ‘RelTol’ and ‘AbsTol’ but nothing change for every possible values, i tried to provide the Jacobian matrix but again it gives the same error.
The initial conditions are consistent because Node_2(0,y0,yp0) = [0 … 0]
I would like to understand why there is this error so that i can find a solution, or i you spot the error in the code i would appreciate.I’m solving a DAE using ode15i. I use the same syntaxs as the example of Robertson in Matlab help
https://it.mathworks.com/help/matlab/ref/ode15i.html?s_tid=doc_ta
The script is
h = 2/2; % h = L/n, L = 2, n = 2

y0 = [0;-2/h^2;1;2/h^2;1/h;-1/h;1/h;0];
yp0 = [
-2.0000
-0.0545
2.0000
0.0545
0
0
0
0];

%The initial conditions must be "consistent", meaning
% that f(T0,Y0,YP0)=0
% With y0 and yp0 given, Node_2(0,y0,yp0) = [0 … 0] so initial conditions
% are consistent

%opt = odeset(‘RelTol’,10^-3,’AbsTol’,10^-6,’Jacobian’,@Jac_Node_2); %Optionnal

tspan = [0 4];
[t,y] = ode15i(@Node_2,tspan,y0,yp0);%,opt);
And the odefunction is :
function res = Node_2(t,y,yp)
h = 2/2;
m = 25000*0.12^2/9.81;

res = [
(y(3) – y(1))/h – y(5);
(y(6)-y(5))/h – m*yp(2);
y(1);
yp(1) – y(2);
(y(8)-y(3))/h – y(6);
(y(7)-y(6))/h – m*yp(4);
yp(3) – y(4);
y(8)
];

end
The problem is that i get the following error :
Warning: Failure at t=0.000000e+00. Unable to meet integration tolerances without reducing the step size below the smallest value allowed (0.000000e+00) at time t.
I tried to change the relative and absolute error tolerance ‘RelTol’ and ‘AbsTol’ but nothing change for every possible values, i tried to provide the Jacobian matrix but again it gives the same error.
The initial conditions are consistent because Node_2(0,y0,yp0) = [0 … 0]
I would like to understand why there is this error so that i can find a solution, or i you spot the error in the code i would appreciate. I’m solving a DAE using ode15i. I use the same syntaxs as the example of Robertson in Matlab help
https://it.mathworks.com/help/matlab/ref/ode15i.html?s_tid=doc_ta
The script is
h = 2/2; % h = L/n, L = 2, n = 2

y0 = [0;-2/h^2;1;2/h^2;1/h;-1/h;1/h;0];
yp0 = [
-2.0000
-0.0545
2.0000
0.0545
0
0
0
0];

%The initial conditions must be "consistent", meaning
% that f(T0,Y0,YP0)=0
% With y0 and yp0 given, Node_2(0,y0,yp0) = [0 … 0] so initial conditions
% are consistent

%opt = odeset(‘RelTol’,10^-3,’AbsTol’,10^-6,’Jacobian’,@Jac_Node_2); %Optionnal

tspan = [0 4];
[t,y] = ode15i(@Node_2,tspan,y0,yp0);%,opt);
And the odefunction is :
function res = Node_2(t,y,yp)
h = 2/2;
m = 25000*0.12^2/9.81;

res = [
(y(3) – y(1))/h – y(5);
(y(6)-y(5))/h – m*yp(2);
y(1);
yp(1) – y(2);
(y(8)-y(3))/h – y(6);
(y(7)-y(6))/h – m*yp(4);
yp(3) – y(4);
y(8)
];

end
The problem is that i get the following error :
Warning: Failure at t=0.000000e+00. Unable to meet integration tolerances without reducing the step size below the smallest value allowed (0.000000e+00) at time t.
I tried to change the relative and absolute error tolerance ‘RelTol’ and ‘AbsTol’ but nothing change for every possible values, i tried to provide the Jacobian matrix but again it gives the same error.
The initial conditions are consistent because Node_2(0,y0,yp0) = [0 … 0]
I would like to understand why there is this error so that i can find a solution, or i you spot the error in the code i would appreciate. ode15i, dae, error MATLAB Answers — New Questions

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