error occurring while solving odes using ode15s
조회 수: 2 (최근 30일)
이전 댓글 표시
function comb_thesis
clc
clear all
global E A B
E = [-3.6264 3.5447 -4.8625 zeros(1,8);-0.3148 -1.9197 -1.1648 zeros(1,8);zeros(3) eye(3) zeros(3,5);zeros(6,11)]
A = [8.5970 -8.3254 9.8331 zeros(1,8);1.0280 2.9897 1.8778 zeros(1,8);zeros(1,3) -0.75 -1 0.25 zeros(1,3) 51.3257 11.2723;zeros(1,3) 0 -2 0 zeros(1,3) 41.5581 7.8378;zeros(1,3) 0.25 1 -0.75 zeros(1,3) -24.3673 -6.2663;zeros(1,3) eye(1,3) -eye(1,3) -0.4488 2.4167;zeros(1,3) 0 1 0 0 -1 0 -0.0898 0.4833;zeros(1,3) 0 0 1 0 0 -1 0.2693 -1.4500;-0.1857 0 -0.1857 zeros(1,6) -eye(1,2);10 0 10 zeros(1,6) 0 -1;zeros(1,11)]
B = [-0.7306 -0.8299 -0.5319;0.4742 0.0304 1.3620;0.0517 -0.2759 0.7068;-0.2241 -0.1379 -0.3965;-0.0517 0.2759 -0.7068;zeros(3);zeros(3)]
tspan = 0:0.1:20;
x0 = [1 0 -1 10 11 6 zeros(1,5)];
size(x0)
opt = odeset('RelTol', 1e-6,'Mass',E);
[~,x] = ode15s(@ode,tspan,x0,opt);
end
function dxdt = ode(t,x)
global A B
dxdt = A*x + B*[exp(-t)*sin(t);0.2*sin(2*t);0.2*sin(3*t)]
end
Errors are-
Error using daeic12 (line 76)
This DAE appears to be of index greater than 1.
Error in ode15s (line 310)
[y,yp,f0,dfdy,nFE,nPD,Jfac] = daeic12(odeFcn,odeArgs,t,ICtype,Mt,y,yp0,f0,...
Error in comb_thesis (line 12)
[~,x] = ode15s(@ode,tspan,x0,opt);
I am getting output but still this kind of errors are showing up. Please Help!
댓글 수: 4
Stephen23
2021년 4월 8일
"What about error that i am facing up?"
Check, double check, triple check your matrices! Perhaps write them in table or CSV file which you can import, just so that they can be written explicitly in a way that can be reviewed visually.
Check the behavior of the ODE you are trying to solve: is it suitable for the solver you have chosen?
채택된 답변
Bjorn Gustavsson
2021년 4월 8일
Check your mass-matrix E and make sure it looks exactly like you expect. The 3 off-diagonal 1s looks peculiar to me. Then you have to read up on the use of the mass-matrix in the documentation, there are rather strict constraints on what type of algebraic equations you can send in to the ODE-functions. Yours might be too complicated.
(
Also remove the globals, just define the ode-function like this instead:
function dxdt = ode(t,x,A,B)
dxdt = A*x + B*[exp(-t)*sin(t);0.2*sin(2*t);0.2*sin(3*t)];
end
and call it like this:
[~,x] = ode15s(@(t,x) ode(t,x,A,B),tspan,x0,opt);
)
HTH
댓글 수: 4
Bjorn Gustavsson
2021년 4월 9일
편집: Bjorn Gustavsson
2021년 4월 9일
When I've had to solve equations of motion in complicated conservative force-fields (where total particle energy is conserved) I'd switched to completely different ODE-integrating schemes (Boris-mover, etc). Since it is not perfectly clear to me what your DAE-system is in that sense I cannot give much better/more extensive advice than this.
추가 답변 (1개)
Sr
2023년 1월 5일
hello, I got the same problem. Have you solved this problem? Any information about this will be appreciated.
참고 항목
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!