[Octave-patch-tracker] [patch #8368] imremap - Change to imremap to reduce memory footprint

[Ian Journeaux]

URL:
  <http://savannah.gnu.org/patch/?8368>

                 Summary: imremap - Change to imremap to reduce memory
footprint
                 Project: GNU Octave
            Submitted by: ijourneaux
            Submitted on: Mon 03 Mar 2014 03:23:29 PM GMT
                Category: None
                Priority: 5 - Normal
                  Status: None
                 Privacy: Public
             Assigned to: None
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any

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Details:

I would propose the following change to imremap to reduce the memory
footprint. I will post a similar change to imresize.

The issue is that meshgrid returns double when single should be sufficient. 

The change involves replacing

[X, Y] = meshgrid(1:columns(Z), 1:rows(Z));

with
XD = linspace (1, columns(Z), columns(Z));
YD = linspace (1, rows(Z), Rows(Z));
XDs = single(XD);
YDs = single(YD);
%# absolute tolerance equality
isequalAbs = @(x,y,tol) (abs(x-y) <= tol );

if(all(isequalAbs(XD, XDs, eps(XDs))) && all(isequalAbs(YD, YDs, eps(YDs)))) 
  XD = XDs;
  YD = YDs;
endif
XDs=[];
YDs=[];
[X, Y] = meshgrid (XD, YD);
XD=[];
YD=[];





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