problem with matrix dimension

I have problems with this system,, it returns DG_DX in an ODE 45, but before i can even run ode 45 I have this message

I checked the dimensions of the vectors

C 1x100

A 1x100

rho 100x1

rho_fuel is a scalar

i tried to make fliplr(rho), inside and outside the function, but it gives always the same message

function DG_dx=flux_dim(G,A,rho,C,rho_fuel ,x)



DG_dx=(-C-A).*(rho-rho_fuel);
DG_dx=DG_dx(:);

end

Answer 1

[Walter Roberson]

You are using a version before R2016b. You will need to code as

DG_dx = bsxfun(@times, (-C-A), (rho-rho_fuel));

The result will be a 100 x 100 matrix, which you will then (:) and return. ode45 will then complain that it is not the same size as the boundary conditions.

Perhaps what you want is instead

DG_dx=(-C-A).'.*(rho-rho_fuel);