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function [t,x] = ny3(field, t0, T, x0, h)
%AB3 Implements the Nystrom three-step ODE solver
%
% Parameters:
% field -- Right hand side function of ODE system: x'=f(t,x)
% t0 -- Initial time
% T -- End time (T > t0)
% x0 -- Initial value
% h -- Size of time step (h <= T-t0)
%
% Outputs:
% t -- [t0; t-0+h, t0+2*h; ...; t0+i*h; ...]
% x -- Column vector containing numerical solution at each time step
q = 2;
n = ceil((T-t0)/h);
t = t0+h*(0:n).';
x = ones(n+1,length(x0));
[t(1:(q+1)), x(1:(q+1),:)] = rk_classical(field, t0, t0+q*h, x0, h);
f2 = feval(field, t(q-1), x(q-1,:).');
f1 = feval(field, t(q), x(q,:).');
for i=(q+1):n
f0 = feval(field, t(i), x(i,:).');
x(i+1,:) = x(i-1,:).' + h*(7*f0-2*f1+f2)/3;
f2 = f1;
f1 = f0;
end
