Numerically approximate f⁻¹(y) by finding x where f(x)=y using bisection search.
This calculator numerically finds x such that f(x) = y using the bisection method. The function must be continuous and the interval [lo, hi] must bracket the solution (f(lo)−y and f(hi)−y must have opposite signs). The method converges to machine precision in about 50 iterations.
Bisection method
Repeat: mid = (lo+hi)/2; if f(mid)-y has same sign as f(lo)-y then lo=mid, else hi=mid
Bisection requires a sign change. If the function is not monotonic on the interval, narrow the interval to a region where it is.
The bisection method converges to approximately 12 decimal places of precision within 100 iterations.