MATLAB: Problems with while loop

while loop

Hi, I have a problem, I want the subtraction d1 to be less than 1 * 10 ^ -15 after several iterations, but the program stays busy.

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"Hi, I have a problem, I want the subtraction d1 to be less than 1 * 10 ^ -15 after several iterations, but the program stays busy."

Well you cannot demand floating point error to be that small.

Double IEEE has about 15 digits relative precision. You compare B1 to (y/k0) which is -7699432.66755457. The most you can demand is error is about

>> tol = eps(y/k0)
tol =
      9.31322574615479e-10

So if you replace the break condition by

tol = eps(y/k0);
while tt>tol
   ...
end

your while loop will stop.

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MATLAB: Do I get “Array indices must be positive integers or logical values” error when using

k is 3.5

So y(k-1) is y(2.5) and y(k-2) is y(1.5). The indexes are not positive integers, hence the error.

Maybe you meant

k = 3;

y(k) = 2 - 0.4 +1.2*y(k-1) -0.72*y(k-2);

MATLAB: Solving a system of 6 differential equations to find a dynamic solution

The bunch of globals called "z1, z2, ..." is really ugly. I would not dare to debug the formula. See http://www.mathworks.com/matlabcentral/answers/1971 for a reliable method to avoid globals, which are evil in general.

If you have calculated the trajectories with ode45, ode23 and a manually code RK4, and you get similar results, you can be sure, that the results are exactly, what you have coded. If you expect something else, either the code is wrong, or your expectations. You can imagine that we cannot debug e.g. the construction of MATBIT. Codes like:

      z4=dh(m,1);
      z5=eh(m,1);
      z6=fh(m,1);
      z7=gh(m,1);

u2=real(C(1,1)*v(2,1)*e1*tt+C(2,1)*v(2,2)*e2*tt+C(3,1)*v(2,3)*e3*tt+C(4,1)*v(2,4)*e4*tt+C(5,1)*v(2,5)*e5*tt+C(6,1)*v(2,6)*e6*tt+EQSOL1(2,1));

prevent understanding and impede debugging. So I have to say: Sorry, I do not think that anybody can find the problem. I would never trust the results of this code, even if they satisfy your expectations.

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Related Solutions

MATLAB: Do I get “Array indices must be positive integers or logical values” error when using

MATLAB: Solving a system of 6 differential equations to find a dynamic solution

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