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function [u,t] = adamsbashforth3(u0,t0,tn,h,f)
//adamsbashforth3 3rd order method solving ODE
// du/dt = f(u,t), with initial
//conditions u=u0 at t=t0. The
//solution is obtained for t = [t0:h:tn]
//and returned in u
umaxAllowed = 1e+100;
t = [t0:h:tn]; u = zeros(t); n = length(u); u(1) = u0;
for j = 1:n-2
if j<3 then
k1=h*f(t(j),u(j));
k2=h*f(t(j)+h,u(j)+k1);
u(j+1) = u(j) + (k2+k1)/2;
end;
if j>=2 then
u(j+2) = u(j+1) + (h/12)*(23*f(t(j+1),u(j+1))-16*f(t(j),u(j))+5*f(t(j-1),u(j-1)));
end;
end;
endfunction
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