Help with error: "??? Error using ==> minus. Matrix dimensions must agree. Error in ==> odenumjac at 148, Fdiff = Fdel - Fvalue(:,ones(1,ny));"

Colin

2012 10 10

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Hello, I'm trying to use matlab to solve a differential algebraic system of equations (DAE), without luck. I'm trying to follow the hb1dae example but encounter this error message: "??? Error using ==> minus. Matrix dimensions must agree. Error in ==> odenumjac at 148, Fdiff = Fdel - Fvalue(:,ones(1,ny));"

Any advice on how to proceed?

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Star Strider 2012-10-10

It would probably help if you posted the relevant parts of your code.

Specifically, what are the sizes of Fdel and Fvalue and what is the value of ny?

Colin 2012-10-10

Thanks for the inquiry.

Fdel, Fvalue, and ny are generated within ODE23t, so I don't know their origin, but the debugger gives these values for them:

ny:2

Fvalue(:,ones(1,ny)): 0.1992 0.1992 -1.0000 -1.0000

Fdel: 0.1992 -1.0000

Here's a simplified version of my script:

Caller:

M = eye(3,3); M(3,3)=0; y0 = [1 1 0]; tspan = [0.99 0.5]; options = odeset('Mass',M,'MassSingular','yes','RelTol',1e-4,'AbsTol',[1e-6 1e-6 1e-6],'Vectorized','on'); [t,y] = ode23t(@batch_DAE_model,tspan,y0,options);

System of Eqs:

function dy = batch_DAE_model(F,y) DSi=1.2; DAl=0.8; dy = [ ((DSi - 1)/(DSi - F*(DSi - 1))^2); ((DAl - 1)/(DAl - F*(DAl - 1))^2); y(1)+y(2)-2];

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