using ODE to solve coupled equations

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Josh 2016-7-1

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评论： Star Strider 2016-7-1

Hi,

I am trying to solve a set of coupled equations but keep getting the error, "Attempted to access x(5); index out of bounds because numel(x)=1."

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Star Strider 2016-7-1

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You need to define ‘x’ as a (7x1) vector of initial conditions in your call to your ODE solver.

Also, you’re going to encounter problems with ‘x’ in these lines, because you have defined it as a vector:

dxdt(1,:) = x*(Vs - vC)/L + y*(vj1 - vC)/L;                             % diL/dt
dxdt(2,:) = x*(-Vs - vj1)/Lp1 + y*(-vj1 - L*(vj1 - vC) - vC)/(L*Lp1);   % diLp1/dt    
dxdt(3,:) = x*(-Vs - vj2)/Lp2 + y*(-vj2 - L*(vj1 - vC) - vC)/(L*Lp2);   % diLp2/dt

I suspect that will throw one of may possible errors about dimensions not agreeing. I have no idea what you’re doing, so I can’t offer a solution.

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Josh 2016-7-1

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I found the problem. In my code

if true
  if (d >= tri)           % switch open
x = 0;
y = 1;
else                    % switch closed
x = 1;
y = 0;
end

I was setting x to 0 or 1 making it now a 1x1. I changed x in the if statement to a and made the corresponding changes in the equations. I don't get that error anymore.

Thanks for the help.