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[Octave-bug-tracker] [bug #41186] image: fspecial disk is not matlab com
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From: |
Joonas Lipping |
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Subject: |
[Octave-bug-tracker] [bug #41186] image: fspecial disk is not matlab compatible |
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Date: |
Thu, 27 Feb 2014 22:49:23 +0000 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:27.0) Gecko/20100101 Firefox/27.0 |
Follow-up Comment #1, bug #41186 (project octave):
I am adding a comment to comply with the warning on the Short Projects wiki
page (for file #30710 below).
I have adjusted the fspecial function 'disk' case. In the (2R+1)x(2R+1) matrix
M that is returned, each element corresponds to a square of size 1 on a grid.
Let there be a disk of radius R centered in the *middle* of the square
corresponding to element m_{R+1,R+1}. Then m_{ij} = p_{ij}/A, where p_{ij} is
the fraction of the corresponding square that is covered by the disk and A =
pi R^2 is the total area of the square.
This appears to give the same values as Matlab's fspecial function, up to
"format long" accuracy.
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