ESQL: Add MV_PSERIES_WEIGHTED_SUM for score calculations used by security solution

[machadoum]

Adds a MV_PSERIES_WEIGHTED_SUM which security solution will use.

This PR created MV_PSERIES_WEIGHTED_SUM function for converting sorted lists of numbers into a bounded score. It is a generalization of the riemann zeta function, but we don't name it because we don't support complex numbers and don't want to make folks think of mystical number theory things. This is just a weighted sum that is adjacent to magic.

A bit of math

Given the general form of p-series:
$$\sum_{n=1}^{\infty} \frac{1}{n^p} = \frac{1}{1^p} + \frac{1}{2^p} + \frac{1}{3^p} ...$$

We multiply every element on the input array by its corresponding term in the equation.

MV_PSERIES_WEIGHTED_SUM([70, 45, 21 , 21, 21], 3)
Where 3 is the p parameter and [70, 45, 21, 21, 21] is the input array

It does the following calculation:
$$(\frac{70}{1^3} + \frac{45}{2^3} + \frac{21}{3^3} + \frac{21}{4^3} + \frac{21}{5^3})$$

[elasticsearchmachine]

Hi @machadoum, I've created a changelog YAML for you.

[elasticsearchmachine]

Pinging @elastic/es-analytical-engine (Team:Analytics)

[nik9000]

I pushed a bit with @Fixed but there's a bug because the generated code uses p as a name and there's a clash.

[nik9000]

Fix for the problem with @Fixed: #111365 (review)

[nik9000]

Fix for the problem with @Fixed: #111365 (review)

Which I merged in.

[ivancea]

LGTM!

[nik9000]

Thanks for all the iterations!

…

On Wed, Jul 31, 2024, 6:08 AM Pablo Machado ***@***.***> wrote: Merged #109017 <#109017> into main. — Reply to this email directly, view it on GitHub <#109017 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABUXIXB6MUEG67DLL5N6WLZPCZTFAVCNFSM6AAAAABIHTEC6WVHI2DSMVQWIX3LMV45UABCJFZXG5LFIV3GK3TUJZXXI2LGNFRWC5DJN5XDWMJTG4YDONJWHAYTSNQ> . You are receiving this because you were mentioned.Message ID: ***@***.***>