A quadratic map bends the recurrence, x -> x^2 + c, so values can climb fast and fractions get ugly; the ledger halts at a chosen step before that happens. It is a toy model of nonlinear feedback, not a real trajectory of a physical system. The exact numbers apply only to the stated c, seed, and stop rule.
A nonlinear update stays exact by keeping the ledger short. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
A nonlinear update can still be exact
With seed one quarter, the training map gives three eighths.
x1=2⋅41(1−41)=83
The example stops before fractions become unreadable
The next state is fifteen thirty-seconds; this lesson does not claim a long-run orbit.