One function returns the correct results, the opposite not. Why?

Question

One function returns the correct results, the opposite not. Why?

AbderRahman (Computer)

(OP)

21 Feb 13 20:46

I have the following function that checks the pixels from `x` that have the membership value `near 1` and sets those pixels in `x` to `1` and return them back. The works pretty well for me:

function c = core(x, y)
tolerance = 0.01;
[ii,jj]=find (abs(y)-1 <= tolerance);
x(ii,jj)=1; % set pixels in x with y=1 to 1
idx=[ii,jj]; % indexes of pixels with y=1
c=x(abs(y)-1 <= tolerance); % values of pixels
end

Now, to the opposite function below. I just want to check the pixels that have membership values values `not equal to one` and since in my case I don't have exactly value `1` and this used `tolerance`. I wrote what I think is the opposite of the above, but my output is an `empty matrix`. Why is that? What should I change in the function below?

function s = support(x, y)
tolerance = 0.01;
[ii,jj]= find (abs(y)-1 > tolerance);
x(ii,jj)=0; % set pixels in x with y~=1 to 0
idx=[ii,jj]; % indexes of pixels with y~=1
s=x(abs(y)-1 > tolerance); % values of pixels
end

Thanks.

GregLocock (Automotive) · Answer 1 · 2013-02-21 21:43:15

your brackets look screwy

Cheers

Greg Locock

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LiteYear (Computer) · Answer 2 · 2013-02-27 17:27:05

Brackets look fine to me. Code also works fine for me:

CODE --> Matlab

>> x = [1 2 3 4 5 6];
>> y = [1.001 1.5 1.005 4 0.995 0.999];
>> core(x, y)

ans =

     1     1     1     1

>> support(x, y)

ans =

     0     0

Not sure why you'd want to do this, but the two functions certainly perform opposite functions and neither returns an empty matrix (unless of course, no values satisfy the condition).

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One function returns the correct results, the opposite not. Why?