One thing that seems to be contributing – the ODE solution should be monotone, but for some values, it seems to break and go “backward” – rather than sampling increasing alpha values, it samples a value that is below the initial value at some point and then blows up.
I’m not sure why this occurs or how to prevent it…
I can change da_ds = 0.00001 whenever ds_da = 0, but this doesn’t really help – the solver never gets past the blow up point.