ExactCalc

1/3 is not 0.33. Pi is not 3.14. Actually 1/3 is in interval [0.33, 0.34] and pi is in interval [3.14, 3.15].

During computation truncating error is accumulating. At end of computation it is needed to know real boundaries of result. The solution is given by interval arithmetic. Simply speaking, because 1/3 is in interval [0.33, 0.34] and 1/7 is in interval [0.14, 0.15], value 1/3 - 1/7 must be in [0.18, 0.2]. Computation can be arbitrary long and complex but interval arithmetic gives interval that contains exact result of computation.

Sometimes is more easy to use numerical unstable algorithm to solve problem. Instability is actually speed of accumulating the truncation error, but it can be decreased arbitrary by using more precise computation. Interval arithmetic provides us control of accumulating truncating error.

To save Your time using CPU time this program provides interpreter of simple programming language based on interval algebra with arbitrary precision arithmetic.