I am facing the problem on ode 45. any one knows help me?

Warning: Failure at t=1.555351e-02. Unable to meet integration tolerances without reducing the step size below the smallest value allowed (2.775558e-17) at time t.

[RAVI MANDAVA]

Dear sir I am attcahing my code also. I am facing the problem at ode45.

Answer 1

[Walter Roberson]

You have a singularity at time 1.555351e-02

[RAVI MANDAVA]

Dear sir, how to rectify this problem. plz help me.

[Torsten]

You should first try another integrator, e.g. ODE15S.

If the problem persists, you should search for errors in your differential equations or in the implementation of your differential equations.

Best wishes

Torsten.

[RAVI MANDAVA]

I tried sir, but it shows same warning

[Steven Lord]

You should show a SMALL segment of code that people reading this question can use to reproduce the behavior you're seeing.

[RAVI MANDAVA]

i am attaching my code also. please help me .

[Walter Roberson]

near line 39, your frewy6 code tries to display t and x, but they are not defined until the line after that.

[Walter Roberson]

Near that t, x(17) starts to become notably larger and positive, and x(18) starts to become even more notably larger negative.

Look at your code near line 107. You write your 6 x 6 d (inertia) terms into x(i,j) . But x is a 24 x 1 input, so writing into x(i,j) results in a 24 x 6 array with the upper 6 x 6 being the values of d and the left edge otherwise being the input x, and the lower right being all 0 (because of automatic 0 extension when you create additional columns.)

And then after that, you never refer to x with two subscripts, continuing to refer to it with one subscript, and you never (that I found) refer to it with a subscript greater than 24, so you never reach into that second column. You do, however, use the updated x(1:6), and you write the d into separate variables like d15 and use those: if you are intentionally writing over parts of x, why not leave x alone and refer to those d variables instead??

Later you have loops such as

c5=0;
for i=5
    for j=1:6
        for k=1:6
           % printf('d(i,j)=%d \t \n',d(i,j));
            c5=c5+(c(i,j,k));
        end
    end

end

as a matter of efficiency and clarity, why not use something like

VEC = @(V) V(:);
c5 = sum(VEC(c(5,:,:)));

(The VEC would only be done once in the code and called upon after that.)

Equivalents:

c5 = sum(reshape(c(5,:,:),[],1));

or

c5 = sum(sum(c(5,:,:),3));