[MSE] iterated sin using Besselfunction 1st kind

[Gottfried]

Excuse me Gottfried... but reading the title I can't resist saying that if any function comes out of iterated sin using Bessel functions then you should call it the Hell function, or call the code Devil.Pari/GP.

Hmm, perhaps getting famous & holy if one eventually finds the sin()-root or perhaps, better: root-sin() ? (however, programming this in "Python", likely drives you out of paradise instead... isn't "Python" an objection-orientated language, btw.?)