Re: Function works with number literal but not with variable

[George]

2009/12/16 John W. Eaton <address@hidden>:
> On 16-Dec-2009, George wrote:
>
> | On Wed, Dec 16, 2009 at 11:36 AM, George <address@hidden> wrote:
> | > imshow doesn't work if an image contains both positive and negative
> | > values. So I tried to write a wrapper for imshow that will scale the
> | > image so that all the elements are positive. So I call imshow from
> | > within my function. The problem is that it doesn't work if I pass the
> | > limits from variables, but it works if I type them as numbers. So this
> | > code doesn't work:
> | >
> | >        minVal = min(min(image));
> | >        maxVal = max(max(image));
> | >        [rows, columns] = size(image);
> | >        normalized = image - ones(rows,columns) * (minVal);
> | >        minVal = min(min(normalized));
> | >        maxVal = max(max(normalized)); % for my test image this is 44.2, I
> | > can see it if I remove the semicolon
> | >        imshow(normalized, [0, maxVal]);
> | >
> | > But it works if I change the last line to this:
> | >
> | >        imshow(normalized, [0, 44.2]);
> | >
> | > Two questions here:
> | >
> | > Why does this happen?
> | > Why doesn't imshow work with images that have both positive and negative 
> values?
> |
> | I found that the problem was that my image was of type 'single'. If I
> | convert it to 'double' imshow works. Is this a bug? I think so.
>
> If you think you've found a bug, then please send a complete bug
> report to the address@hidden list.  Please see
> http://www.octave.org/bugs.html to see what information you should
> include in your report.  At the very least, you should include the
> version of Octave you are using, a complete example that can be used
> to duplicate the problem, what you see when running your example, and
> what you expect to see.
>
> jwe
>

Ok so from looking at the code you don't see anything wrong?