Solving coupled ODE's by ode45

Question

sara kian 2013-3-9

关闭： MATLAB Answer Bot 2021-8-20

Hi, I am trying to solve a set of 4 coupled equations but I don't know which initial condition I should use? would you please help me?

Maybe I have to define initial condition in a not-zero position,so which command I have to use?

Thanks,

Sara

Azzi Abdelmalek 2013-3-9

Where are your equations?

sara kian 2013-3-9

Hi; I attached equations,I have to define boundary condition for A,B

Regards, Sara

dx_dt(1)=((-1j*26.46*10^7)*exp(-j*1.252*(10^7)*t))*x(2)+((-1j*7.686*10^7)*exp(-j*1.252*(10^7)*t))*x(4);

dx_dt(3)=((-1j*7.686*10^7)*exp(-j*1.252*(10^7)*t))*x(2)+((-1j*36.54*10^7)*exp(-j*1.252*(10^7)*t))*x(4);

dx_dt(2)=((1j*26.46*10^7)*exp(j*1.252*(10^7)*t))*x(1)+((1j*7.686*10^7)*exp(j*1.252*(10^7)*t))*x(3);

dx_dt(4)=((1j*7.686*10^7)*exp(j*1.252*(10^7)*t))*x(1)+((1j*36.54*10^7)*exp(j*1.252*(10^7)*t))*x(3);

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Answer 1

Jan 2013-3-10

Note: 7.686e7j is much faster than 1j*7.686*10^7.

You do not need a special command to get the initial values. You can set it to any [1 x 4] vector, which satisfy your problem.