MATLAB: Eliminate integral from symbolic differential system solution

differential equationsintegrationsymbolic

I use the Symbolic Toolbox to solve the following system:
sol_ct = dsolve(...
    diff(cb) == -k4*cb + k3*cf, ...
    diff(cf) == k4*cb - (k1/Vd + k3)*cf + k1*((A1*t-A2-A3)*exp(-L1*t) + A2*exp(-L2*t) + A3*exp(-L3*t)),...
    cf(0) == 0, cb(0) == 0,'IgnoreAnalyticConstraints',true);
The odd thing is that the solutions of both cf and cb contain integrals like:
int(exp(-(x*(2*L1 + 2*L2 + 2*L3 - k2 - k3 - k4 + (k2^2 + 2*k2*k3 - 2*k2*k4 + k3^2 + 2*k3*k4 + k4^2)^(1/2)))/2)*(heaviside(tau - x) - 1)*(A2*exp(L1*tau + L2*x + L3*x) - A2*exp(L2*tau + L1*x + L3*x) + A3*exp(L1*tau + L2*x + L3*x) - A3*exp(L3*tau + L1*x + L2*x) + A1*tau*exp(L1*tau + L2*x + L3*x) - A1*x*exp(L1*tau + L2*x + L3*x)), x == 0..t)
Due to these integrals, it is not possible to export these solutions using MatlabFunction, which I require for further least squares fitting. Thus far I failed to either evaluate these integrals to find a way to export these solutions. Any help would be greatly appreciated!

Best Answer

I managed to solve the problem my rewriting the integrals to the proper syntax and evaluating them using the Toolbox. My substituting this result into the original equation I was able to obtain the solutions without unevaluated integrals.
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