Implement support for negative divisor in the BigNumber and Fraction implementation of function mod

[travellingprog]

Describe the bug

gcd(x, y) fails if y is negative and if x or y is a BigNumber. The gcd(x, y) function internally calls the mod(x, y) function. Unfortunately, the mod(x, y) function has been set to fail when a BigNumber is involved, if the divisor y is negative.

Potential solution would be for gcd(x, y) to internally call mod(x, abs(y)) instead.

To Reproduce

const { BigNumber, gcd } = require('mathjs');
gcd(-2, BigNumber(12)); // 2  -- No issue
gcd(BigNumber(12), -2); // Uncaught Error: Cannot calculate mod for a negative divisor

[josdejong]

Good point. We recently improved the number implementation of the function mod (used by gcd) to support negative divisors, but haven't adjusted the BigNumber and Fraction implementations. It shouldn't be hard to adjust this and copy the number implementation of mod to BigNumber and Fraction.

Anyone interested in picking this up? Help would be welcome.

[josdejong]

Fixed via 8679c07 (not yet published)

[josdejong]

Published now in v12.1.0