From 6d3cbd83e9c5e49915e84003a9fc0597eafbe14b Mon Sep 17 00:00:00 2001
From: Michael Winter <mwinter@unboundedpress.org>
Date: Mon, 16 Mar 2026 14:53:13 +0100
Subject: [PATCH] Fix cent_diffs to store signed values

- harmonic_space.py: remove abs() to store signed cent differences
- graph.py: melodic threshold now uses abs(cents) for magnitude
- Change melodic power from 2 to 3 for sharper penalization

This fixes contrary_motion factor which was broken (always 0 due to absolute values)
---
 src/graph.py          | 15 ++++++++-------
 src/harmonic_space.py |  2 +-
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/src/graph.py b/src/graph.py
index 124be70..be0cc1e 100644
--- a/src/graph.py
+++ b/src/graph.py
@@ -277,9 +277,9 @@ class PathFinder:
         """Returns continuous score based on melodic threshold.
 
         - cents == 0: score = 1.0 (no movement is always ideal)
-        - Below min (0 < cents < min): score = (cents / min)^2
+        - Below min (0 < cents < min): score = (cents / min)^3
         - Within range (min <= cents <= max): score = 1.0
-        - Above max (cents > max): score = ((1200 - cents) / (1200 - max))^2
+        - Above max (cents > max): score = ((1200 - cents) / (1200 - max))^3
 
         Returns product of all voice scores.
         """
@@ -293,12 +293,13 @@ class PathFinder:
 
         product = 1.0
         for cents in cent_diffs:
-            if cents == 0:
+            abs_cents = abs(cents)
+            if abs_cents == 0:
                 score = 1.0
-            elif cents < melodic_min:
-                score = (cents / melodic_min) ** 2
-            elif cents > melodic_max:
-                score = ((1200 - cents) / (1200 - melodic_max)) ** 2
+            elif abs_cents < melodic_min:
+                score = (abs_cents / melodic_min) ** 3
+            elif abs_cents > melodic_max:
+                score = ((1200 - abs_cents) / (1200 - melodic_max)) ** 3
             else:
                 score = 1.0
             product *= score
diff --git a/src/harmonic_space.py b/src/harmonic_space.py
index 6563a87..4ac4837 100644
--- a/src/harmonic_space.py
+++ b/src/harmonic_space.py
@@ -258,7 +258,7 @@ class HarmonicSpace:
                 for src_idx, dest_idx in movements.items():
                     src_pitch = c1.pitches[src_idx]
                     dst_pitch = c2_transposed.pitches[dest_idx]
-                    cents = abs(src_pitch.to_cents() - dst_pitch.to_cents())
+                    cents = src_pitch.to_cents() - dst_pitch.to_cents()
                     cent_diffs.append(cents)
 
                 source = list(c1.pitches)