Solve DAEs in MATLAB | Omar Bin Yusuf

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Discussion Overview

The discussion revolves around solving differential-algebraic equations (DAEs) in MATLAB, specifically focusing on a set of equations presented by a participant. The scope includes technical explanations and potential methods for implementation in MATLAB.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant presents a set of DAEs and seeks suggestions for solving them in MATLAB, mentioning the dependency of the mass matrix on the dependent variables.
  • Another participant suggests consulting MATLAB help documentation, indicating that functions like ode15 or ode23 may be suitable for solving the DAEs.
  • A different participant notes that while ode15s is mentioned in the MATLAB help for solving DAEs, the mass matrix being dependent on the variables complicates the evaluation of M.
  • One participant expresses a preference for using ode45 instead of the other suggested functions.
  • A request for further elaboration on the idea of using ode45 is made, indicating a need for more detailed guidance.

Areas of Agreement / Disagreement

Participants express differing opinions on which MATLAB function is most appropriate for solving the DAEs, with no consensus reached on a specific approach or method.

Contextual Notes

The discussion highlights the complexity introduced by the mass matrix's dependency on the dependent variables, which may affect the choice of numerical methods for solving the DAEs.

Who May Find This Useful

Individuals interested in numerical methods for solving differential-algebraic equations, particularly in the context of MATLAB programming.

oby7842
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I have problem in solving following DAE's:

1. 0 = X*U1*C4+X*U2*C4 - 1

2. Re*C1*(U1+U2)*U1' +Re*C2*(U1^2+U2)*U2'= X*(U1*C2+U1*U2+U2*C3)+(1/X)*(U1+U2)

here X is the independent variable and U1 and U2 depend on X and others are constants.I need to solvethis DAE's in matlab. To solve in MATLAB i have following Mass matrix and function:

M=[0 0 ; Re*C1*(U(1)+U(2)) Re*C2*(U(1)^2+U(2))]; U'=[U(1)' ; U(2)'] ;

f = [ X*U1*C4+X*U2*C4 - 1 ; X*(U1*C2+U1*U2+U2*C3)+(1/X)*(U1+U2) ];

can you give me any suggestion how can I solve this problem in matlab? I will appreciate any kind of suggestion in this regard. I would be grateful also if I get any kind of hints to solve the Mass matrix. thanks for reading my problem.

Omar Bin Yusuf
 
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go thru MATLAB help..its explicitly given there
i think ode15 or ode23 will suit ur purpose..
 
yeah in MATLAB help its says that ode15s can solve this type DAE's. But my Mass matrix M is dependent of U(dependent variable)...I have example to solve this type of problem when Mass matrix is constant. But how can I evaluate value of M?
 
i prefer using ode45 for dat...
 
Can you please elaborate the idea a bit?? It will be a great help for me. thanks
 

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