PT vector

PT vector is a method for storing large numbers based on power towers. It is employed in Hypercalc.

A PT vector [a,b] consists of a nonnegative integer a and a floating-point number b. The numerical interpretation of this vector is

\[[a,b] = \text{sgn}(b) \cdot (10 \uparrow 10 \uparrow \cdots \uparrow 10 \uparrow |b|)\]

where there are a copies of 10.