[Python] Implicit solve_ivp cuts down the number of points I want solution for

I tried using both explicit and implicit methods, where my t_eval is array of size 55. The explicit (default method) outputs an array of size (1x55) which is what I expected.



Where as when I try the implicit 'BDF' method I see only the first two values are stored in my solution:



Not sure if it is related to the events thing or something else. The problem I am solving seems stiff so implicit method might help me. I tried changing the step size by using scipy.integrate.BDF directly but it still did not work. This is the code sample I use for both instances:

sol = solve_ivp(F, [0.1, 1.1], [c_p - h_p[0]], t_eval=h_p)

sol = solve_ivp(F, [0.1, 1.1], [c_p - h_p[0]], t_eval=h_p,
method='BDF', jac=jac)

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