valLast = [];
y0prime = -2:.5:2;

% dynamics for linear problem y'' + pi^2 y / 4 = 0
function yp = yprime(x, y)
  yp = zeros(size(y));
  yp(1) = y(2);
  yp(2) = -y(1)*pi^2/4;
end

% dynamics for nonlinear problem of Example 12.5
function yp = yprime(x, y)
  yp = zeros(size(y));
  yp(1) = y(2);
  yp(2) = -y(2)^2/y(1);
end

for jj = 1:length(y0prime)
  clear t y
  vopt = odeset("RelTol",1e-5,"AbsTol",1e-5,"InitialStep",.05,"MaxStep",.1);
  [t, y] = ode45(@yprime, [0; 1], [0; y0prime(jj)], vopt);
% [t, y] = ode45(@yprime, [1; 3], [sqrt(2); y0prime(jj)], vopt);
  valLast = [valLast y(length(t), 1)];
end

plot(y0prime, valLast, 'b*')