From 9e8648bed7d626d35c0b502da6ec41f1cfef8fc8 Mon Sep 17 00:00:00 2001
From: Damien Elmes <git@ichi2.net>
Date: Wed, 11 Jul 2018 22:18:46 +1000
Subject: [PATCH] differentiate easy button more when reviewing early

apply half the easy bonus post ivl calculation, or else very early
reviews with longer intervals appear to have the same intervals as
answering 'good'
---
 anki/schedv2.py       | 12 ++++++------
 tests/test_schedv2.py |  4 ++--
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/anki/schedv2.py b/anki/schedv2.py
index d310117ec..2287621ce 100644
--- a/anki/schedv2.py
+++ b/anki/schedv2.py
@@ -963,7 +963,7 @@ select id from cards where did in %s and queue = 2 and due <= ? limit ?)"""
 
         conf = self._revConf(card)
 
-        easyBonus = 0
+        easyBonus = 1
         # early 3/4 reviews shouldn't decrease previous interval
         minNewIvl = 1
 
@@ -975,15 +975,15 @@ select id from cards where did in %s and queue = 2 and due <= ? limit ?)"""
         elif ease == 3:
             factor = card.factor / 1000
         else: # ease == 4:
-            factor = card.factor / 1000 * conf['ease4']
-            # add an extra day, so early reviews have an easy interval nominally
-            # different from the good answer
-            easyBonus = 1
+            factor = card.factor / 1000
+            ease4 = conf['ease4']
+            # 1.3 -> 1.15
+            easyBonus = ease4 - (ease4-1)/2
 
         ivl = max(elapsed * factor, 1)
 
         # cap interval decreases
-        ivl = max(card.ivl*minNewIvl+easyBonus, ivl)
+        ivl = max(card.ivl*minNewIvl, ivl) * easyBonus
 
         ivl = self._constrainedIvl(ivl, conf, prev=0, fuzz=False)
 
diff --git a/tests/test_schedv2.py b/tests/test_schedv2.py
index 96c0d48ee..30c25efd6 100644
--- a/tests/test_schedv2.py
+++ b/tests/test_schedv2.py
@@ -679,7 +679,7 @@ def test_filt_reviewing_early_normal():
     assert d.sched.nextIvl(c, 1) == 600
     assert d.sched.nextIvl(c, 2) == int(75*1.2)*86400
     assert d.sched.nextIvl(c, 3) == int(75*2.5)*86400
-    assert d.sched.nextIvl(c, 4) == int(75*2.5*1.3)*86400
+    assert d.sched.nextIvl(c, 4) == int(75*2.5*1.15)*86400
 
     # answer 'good'
     d.sched.answerCard(c, 3)
@@ -702,7 +702,7 @@ def test_filt_reviewing_early_normal():
 
     assert d.sched.nextIvl(c, 2) == 60*86400
     assert d.sched.nextIvl(c, 3) == 100*86400
-    assert d.sched.nextIvl(c, 4) == 101*86400
+    assert d.sched.nextIvl(c, 4) == 114*86400
 
 def test_filt_keep_lrn_state():
     d = getEmptyCol()