I have to solve a 1D ODE depending on a parameter r and compare the solutions for different values of the parameter. In particular I want to make a 3d plot with the parameter r and the time t as (x,y) and the solution g(r,t) as z. I am solving the ode with ode45 but for different values of r the solver needs more and more steps, as in fact for r larger than a critical value my solution always explodes for mathematical reasons. Hence I have vectors of different size for every r.

How can I force ode45 to use an exact same number of steps?

Or how can I refine solution that I have to achieve the same size?

Or how can I make such a 3d plot with y,z vectors all of different size for every x?

Thank you

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