polarstoat / bigint-factorial Goto Github PK

During the performance testing for #2 , it was discovered that very large factorial calculations using the current method of recursion can cause the call stack size to be exceeded.

A Stack Overflow answer suggests this can be fixed by wrapping the recursive function call in a setImmediate function.

It's not yet known at exactly what size factorial calculation the maximum call stack size will be exceeded.

Currently the package only accepts input as type BigInt, it would be potentially be more useful to also accept input as type Number.

This would need checks to ensure the Number is correctly converted to a BigInt.

It may be faster to use a for loop to calculate the factorial, rather than the current method of recursion.

Some basic performance testing should be done to find which is the fastest.

Negative factorials cannot be computed.

The factorials of negative integers cannot be computed, since for n = 0, the recurrence relation,

involves a division by zero. (Thukral, 2014)

However, the idea of applying the concept of factorials to negative integers has been raised before (Thukral, 2014), but there does not appear to be a consensus on how this should be done, or even if it can be done whilst still being considered a factorial. This kind of maths is highly complex and far beyond the scope of this package, so negative input should throw a RangeError.

Thukral, A.K. Factorials of real negative and imaginary numbers - A new perspective. SpringerPlus 3, 658 (2014). https://doi.org/10.1186/2193-1801-3-658

Currently the package only supports the CommonJS style module.exports syntax. Node.js (and modern browsers) now support ES modules natively, and have done for a while. Supporting this style of import could those using ES module syntax.