Solve set of 8 first order ODE's in Octave (matlab)

I have a set of 8 ODE's such that dT/ds = H T and T(a) = I (Indentity) H is an 8x8 constant matrix included below. I am looking for the Octave code to solve for T(b) where for example a = 5, b = 20 I would also be interested in having the solution coded in c++ using the Eigen library ([login to view URL]). If this goes well I have a couple more very similar projects. One would be where the matrix H(s) is a 4x4 matrix but not constant. It would be a function of s. function ret = H(s) % This function in constant! Not a function of s ret = zeros (8, 8); m = 1; R = 27; E = 20E6; t = 1.5; nu = 0.3; ret(2,1) = m/R; ret(1,2) = -nu*m*R; ret(6,2) = 2*pi*E*t*m*m/R; ret(7,2) = 2*pi*E*t*m/R; ret(1,3) = -nu/R; ret(4,3) = -nu*m*m/(R*R); ret(6,3) = 2*pi*E*t*m/R; ret(7,3) = 2*pi*E*t/R*(1+t*t*m*m*m*m/(12*R*R)); ret(3,4) = -1; ret(8,4) = pi*E*t*t*t*m*m/(3*(1+nu)*R); ret(1,5) = (1-nu*nu)/(2*pi*E*t*R); ret(6,5) = nu*m/R; ret(7,5) = nu/R; ret(2,6) = (1+nu)/(pi*E*t*R); ret(5,6) = -m/R; ret(8,7) = 1; ret(4,8) = 6*(1-nu*nu)/(pi*E*t*t*t*R); ret(7,8) = nu*m*m/(R*R); % Everything else is zero endfunction