[issue36027] Consider adding modular multiplicative inverse to the math module

[Raymond Hettinger]

Raymond Hettinger <raymond.hettinger at gmail.com> added the comment:

> +1 for the pow(value, -1, modulus) spelling. It should raise
> `ValueError` if `value` and `modulus` are not relatively prime.

> It would feel odd to me _not_ to extend this to 
> `pow(value, n, modulus)` for all negative `n`, again
> valid only only if `value` is relatively prime to `modulus`.

I'll work up a PR using the simplest implementation.  Once that's in with tests and docs, it's fair game for someone to propose algorithmic optimizations.

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<https://bugs.python.org/issue36027>
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