function [t, u] = eulerivp(dudt, tspan, u0, n)
% EULERIVP   Euler's method for a scalar initial-value problem.
%
% Input:
%   dudt    defines f in u'(t)=f(t,u). (function of two vars)
%   tspan   endpoints of time interval (2-vector)
%   u0      initial value (scalar) 
%   n       number of time steps (integer)
% Output:
%   t       selected nodes  (vector, length n+1)
%   u       solution values   (vector, length n+1)
%
    a = tspan(1);  
    b = tspan(2);
    h = (b-a)/n;
    t = a + (0:n)'*h;
    u = zeros(n+1, 1);
    u(1) = u0;
    for i = 1:n
        u(i+1) = u(i) + h*dudt(t(i), u(i));
    end
end