Easiness for Grade-2 is different than for SM-2

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seanm...@gmail.com

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Jun 27, 2014, 12:30:20 PM6/27/14
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Hi Peter, I know you wrote this all a while back, but I was just taking a look at your easiness code....

if timing in ["LATE", "ON TIME"]:
if new_grade == 2:
card.easiness -= 0.16 !!! Particularly this figure.
if new_grade == 3:
card.easiness -= 0.14
if new_grade == 5:
card.easiness += 0.10
if card.easiness < 1.3:
card.easiness = 1.3

It seems your easiness adjustment when you grade 2 is a bit different to the SM-2 algorithm. Was wondering why you decided to go with the -0.16 figure, or if it was an oversight, or perhaps just my maths is wrong.

http://www.supermemo.com/english/ol/sm2.htm

EF':=EF-0.8+0.28*q-0.02*q*q

So for example if you had an easiness of 2.5 new grade of 2, it would give...

EF' = 2.5 - 0.8 + 0.28*2 - 0.02*2*2
EF' = 2.5 - 0.8 + 0.56 - 0.08
EF' = 2.5 - 0.32

... which is twice your adjustment.


The following ones work out the same as in Super-Memo 2

Example of grade 3

EF' = 2.5 - 0.8 + 0.28*3 - 0.02*3*3
EF' = 2.5 - 0.8 + 0.84 - 0.18
EF' = 2.5 - 0.14

Example of grade 4

EF' = 2.5 - 0.8 + 0.28*4 - 0.02*4*4
EF' = 2.5 - 0.8 + 1.12 - 0.32
EF' = 2.5 - 0

Example of grade 5

EF' = 2.5 - 0.8 + 0.28*5 - 0.02*5*5
EF' = 2.5 - 0.8 + 1.4 -0.5
EF' = 2.5 + 0.1

Peter Bienstman

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Jun 28, 2014, 4:46:03 AM6/28/14
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Hi,

The code is not exactly SM2, but has some little tweaks. It's a long
time ago since I wrote this, though...

Peter

Citeren seanm...@gmail.com:
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