MATLAB: How to pass out a vector of extra parameters using ODE15s

evalinvectors from ode to ws

I'm writing up a code to solve a set of i differential equations and for each equation, I have three important parameters, which I need to export to the WS. I've tried to use evalin, since this was useful when I passed out a single variable.
Now I have to export a vector and I get the following error: "Error using evalin Undefined function 'aw_v' for input arguments of type 'double'."
This is part of the code:
for i=2:(par.nl-1)
          % Moisture content in the solids
          eqn2=@(phi_v)(1-par.epsilon)*rho_sv.*phi_v+par.epsilon*par.rho_a*((par.Psat/(0.0288*par.P))*(1-exp(-0.0004373*(par.T+57.926).*phi_v^(1.2626))))/(55.5556-((55.5556*par.Psat)/par.P)*(1-exp(-0.0004373*(par.T+57.926).*phi_v^(1.2626))))-W(i);
          phi_v(i)=fsolve(eqn2, par.phi); phi_v(i)=double(phi_v(i));
          % Water activity     
          aw_v(i)=isotherm(phi_v(i),par);
          % Humidity    
          H_v(i)=definition(aw_v(i),par);
          % Water vapour    
          WV(i)=par.epsilon*par.rho_a*H_v(i);
          dO(i)=(1/(par.epsilon.*par.Vt(i)))*(par.epsilon.*par.At(i)*par.D_O.*(O(i-1)-O(i))/par.dz-(1-par.epsilon)*par.rho_s.*par.Vt(i)*r_O-par.epsilon.*par.At(i+1)*par.D_O.*(O(i)-O(i+1))/par.dz);
          dC(i)=(1/(par.epsilon.*par.Vt(i)))*(par.epsilon.*par.At(i+1)*par.D_C*(C(i+1)-C(i))/par.dz+(1-par.epsilon)*par.rho_s.*par.Vt(i)*r_C-par.epsilon.*par.At(i)*par.D_C*(C(i)-C(i-1))/par.dz);
          dW(i)=(1./par.Vt(i))*(par.epsilon.*par.At(i+1)*par.D_W*(WV(i+1)-WV(i))*(1/par.epsilon)/par.dz-par.epsilon.*par.At(i)*par.D_W*(WV(i)-WV(i-1))*(1/par.epsilon)/par.dz);
          evalin('base', 'aw_v(i) = aw_v(i)'); evalin('base', 'H_v(i) = H_v(i)');  evalin('base', 'phi_v(i) = phi_v(i)');
      end
About this part: phi_v(i)=double(phi_v(i)); I find out that it is necessary since the outcome of the fsolve needs to be double for entering my function isotherm.
I really appreciate all your comments.

Best Answer

assignin('base', 'aw_v(i)', aw_v(i));
assignin('base', 'H_v(i)', H_v(i));
assignin('base', 'phi_v(i)',  phi_v(i));
Beware: the results you will get in the base workspace will reflect whatever the final invocation of your ode function happened to calculate. The final invocation will not typically correspond to the final time. The ode functions do not evaluate only at the specified times: they evaluate at whatever times and boundary conditions they feel necessary in order to meet the integration tolerances, and they use the information to predict the results at the given times. If I remember correctly, ode15s will never move backwards in time, but some of the other routines like ode45 can move backwards in time.
If you need the results as of some particular time or boundary condition, then you are better off putting the calculation code into a function that is called by the ode function, and then calling the function "by hand" afterwards passing in the final time and boundary conditions output by the ode15s routine.
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