# Error message odeargumen​ts(FcnHand​lesUsed, solver_name, ode, tspan, y0, options, varargin);

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Chris Li on 20 Apr 2021
Answered: William Rose on 20 Apr 2021
function [dydt, NA, NB, Ff] = myode(t, y, n)
%%Part1 Assign values to the system (can be changed)
m = 10; %kg
P = 100; %N
uk = 0.5; %dimensionless
us = 0.8; %dimensionless
B = 0.6; %width m
H = 1.8; %height of refrigerator m
d = 1.5; %height of pulling force m
I = (1/12)*m*(B^2+H^2); %Mass Moment of inertia
g = 9.81; %gravity acceleration
theta = y(5);
Sth = sin(theta);
Cth = cos(theta);
switch n
case 3 %No slip; No tip
%[NA, NB, Ff, ax, ay, alpha]
A = [0, 0, 1, 0, 0, 0;...
1, 1, 0, 0, 0, 0;...
-B/2, B/2, -(H/2), 0, 0, 0];
B = [P; m*g; (d-H/2)*P];
X = A\B;
dydt = [y(2), X(4); y(4), X(5); y(6), X(6)];
NA = X(1); NB = X(2); Ff = X(3);
case 4 %No tip; Slip
%[NA, NB, Ff, ax, ay, alpha]
A = [0, 0, 1, m, 0, 0;...
1, 1, 0, 0, 0, 0;...
-B/2, B/2, -(H/2), 0, 0, 0;...
uk, uk, -1, 0, 0, 0];
B = [P; m*g; (d-H/2)*P; 0];
X = A\B;
dydt = [y(2), X(4); y(4), X(5); y(6), X(6)];
NA = X(1); NB = X(2); Ff = X(3);
case 5 %No slip; B Tip
%[NA, NB, Ff, ax, ay, alpha]
A = [0, 0, 1/2, m, 0, 0;...
0, 1, 0, 0, -m, 0;...
0, B/2, -(H/4), 0, 0, I;...
0, 0, 0, -1, 0, (B/2)*Sth-(H/2)*Cth;...
0, 0, 0, 0, -1, -(B/2)*Cth-(H/2)*Sth];
B = [P; m*g; (d-H/2)*P; ...
y(6)^2*(-B*Cth/2-H*Sth/2); y(6)^2*(-B*Sth/2+H*Cth/2)];
X = A\B;
dydt = [y(2), X(4); y(4), X(5); y(6), X(6)];
NA = X(1); NB = X(2); Ff = X(3);
case 6 %Slip; Tip
%[NA, NB, Ff, ax, ay, alpha]
A = [0, 0, 1/2, m, 0, 0;...
0, 1, 0, 0, -m, 0;...
0, B/2, -(H/4), 0, 0, I;...
0, 0, 0, -1, 0, (B/2)*Sth-(H/2)*Cth;...
0, 0, 0, 0, -1, -(B/2)*Cth-(H/2)*Sth;...
0, -uk, 1, 0, 0, 0];
B = [P; m*g; (d-H/2)*P; ...
y(6)^2*(-B*Cth/2-H*Sth/2); y(6)^2*(-B*Sth/2+H*Cth/2); 0];
X = A\B;
dydt = [y(2), X(4); y(4), X(5); y(6), X(6)];
NA = X(1); NB = X(2); Ff = X(3);
end
When I call this function with:
myode = @myode;
[T,X]=ode45(myode,[0,10],[0,0,0,0,0,0], 5);
IT always show error message:
odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0, options, varargin);

William Rose on 20 Apr 2021
Your function myode() returns 4 quantities: dydt, NA, NB, and Ff.
function [dydt, NA, NB, Ff] = myode(t, y, n)
I'm pretty sure ode45() wants only the vector dydt, so change it to
function dydt = myode(t, y, n)
I suspect that will help. Try it. The change to the first line may be all that is needed. There'll probably be warning messages saying that the values assigned to NA, NB, Ff are not used. You can delete the code for those, or just leave it and not worry abou tthe warnings.