Best Rational Approximation
Given a real number $x$ in the range from 0 to 10 and a positive integer $n$, this calculator uses the Stern-Brocot tree to find the best rational approximation $\displaystyle\frac{a}{b}$, where $b$ is less than or equal to $n$, of $x$.
You can input $x$ as numbers like 3.14159, 1.414, 0.5 or mathematical expressions that can be evaluated to real numbers like sin(0.5), sqrt(2), pi/2, etc.