It's magic. R2017a gives a different result from R2016a/b with the following simple code...
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Shogo Muramatsu
il 10 Apr 2017
Risposto: Prerana Paravastu
il 20 Nov 2017
R2017a gives a different result from R2016a/b with the following code:
I = magic(16); H = magic(4); imfilter(I,H,'circular')
Has the implementation of imfilter been changed?
It is a huge problem for me.
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Walter Roberson
il 10 Apr 2017
Yes, the implementation did change; I do not see any release notes saying so, though.
I see in R2016b that non-separable filters have two branches: filterSingle2DWithConv() for single(), and filterPartOrWhole() for everything else. filterPartOrWhole() calls mex routines to do the work. You are using double(), so you would get the "everything else" mex routines.
I see in R2017a that non-separable filters have three branches: filterDouble2DWithConv() for double() for 2D arrays; filterDouble2DWithConv() (same routine) for double() with 3D arrays; and filterPartOrWhole() otherwise. (Notice filterSingle2DWithConv is gone and handled by filterPartOrWhole() now.) You are using double(), so you get the new filterDouble2DWithConv() routine. It calls upon conv2() to do the work.
I think you would be justified in filing a bug report on this.
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