@Tyyppi_77 Lets check by assuming the facts and seeing if that implies what we want
so bisection will find `t` where `f(t) = 0`, so start from your equation
f(t) = cubic_bezier(0, x1, x2, 1, t) - x
and replace f(t) with 0
cubic_bezier(0, x1, x2, 1, t) - x = 0
cubic_bezier(0, x1, x2, 1, t) = x
Sounds like the usual, @Jon. I'm almost sure at this point that they just add random charges here and there to get money out of the people who don't notice or are too lazy and/or incapable of fighting back
Literally every single person I know, with every single phone and internet provider, has been able to find some charges somewhere that they did not rightfully incur.
And have been able to get the charges cancelled and refunded over the phone in most cases
I already investigated using the closed form solution directly... and that requires you to either 1. implement complex numbers in C++ (ugh) or 2. manipulate your formula to operate in the entirely real domain (ugh)
But he said this: "I was like a boy playing on the sea-shore, and diverting myself now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me."