`glicko2_common`

Shared internal Glicko-2 numeric helpers for rating updates, volatility search, and scale conversions.

| Availability: | logtalk_load(ranking_protocols(loader))

| Author: Paulo Moura | Version: 1:0:0 | Date: 2026-05-02

| Compilation flags: | static

| Uses: | :ref:`avltree <avltree/0>`

| Remarks: | (none)

| Inherited public predicates: | (none)

.. contents:: :local: :backlinks: top

Public predicates

(no local declarations; see entity ancestors if any)

Protected predicates

.. index:: update_item_parameters/10 .. _glicko2_common/0::update_item_parameters/10:

update_item_parameters/10 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Computes the simultaneous Glicko-2 rating, deviation, and volatility update for one item over a rating period using the current dictionaries and aggregated game results.

| Compilation flags: | static

| Template: | update_item_parameters(Item,ItemResults,Ratings,Deviations,Volatilities,Tau,VolatilityTolerance,UpdatedRating,UpdatedDeviation,UpdatedVolatility) | Mode and number of proofs: | update_item_parameters(+term,+list(compound),+compound,+compound,+compound,+number,+number,-number,-number,-number) - one

.. index:: to_mu/2 .. _glicko2_common/0::to_mu/2:

to_mu/2 ^^^^^^^^^^^

Converts a rating on the external Glicko scale to the internal mu scale.

| Compilation flags: | static

| Template: | to_mu(Rating,Mu) | Mode and number of proofs: | to_mu(+number,-number) - one

.. index:: to_phi/2 .. _glicko2_common/0::to_phi/2:

to_phi/2 ^^^^^^^^^^^^

Converts a rating deviation on the external Glicko scale to the internal phi scale.

| Compilation flags: | static

| Template: | to_phi(Deviation,Phi) | Mode and number of proofs: | to_phi(+number,-number) - one

.. index:: to_rating/2 .. _glicko2_common/0::to_rating/2:

to_rating/2 ^^^^^^^^^^^^^^^

Converts a value on the internal mu scale back to the external Glicko rating scale.

| Compilation flags: | static

| Template: | to_rating(Mu,Rating) | Mode and number of proofs: | to_rating(+number,-number) - one

.. index:: to_deviation/2 .. _glicko2_common/0::to_deviation/2:

to_deviation/2 ^^^^^^^^^^^^^^^^^^

Converts a value on the internal phi scale back to the external Glicko rating-deviation scale.

| Compilation flags: | static

| Template: | to_deviation(Phi,Deviation) | Mode and number of proofs: | to_deviation(+number,-number) - one

Private predicates

(no local declarations; see entity ancestors if any)

Operators

(none)