New subject: Convolve returning zero array

15 Dec 2003

      Hi Peter,

At first I used numarray 0.6. This morning I have installed 0.8 but the
results are the same. I will try the convolve functions in the nd_image
package.

Thanks,

Remco Jager

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|---------+---------------------------->
|         |           Peter Verveer    |
|         |                 |
|         |                            |
|         |           15/12/2003 12:04 |
|         |                            |
|---------+---------------------------->
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  |                                                                                                                              |
  |       To:       R.Jager@mapperlithography.com, numpy-discussion@lists.sourceforge.net                                        |
  |       cc:                                                                                                                    |
  |       Subject:  Re: [Numpy-discussion] Convolve returning zero array                                                         |
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...
Hi list,
I already posted this on the numarray forum on freshmeat, but Jay T
Miller
advised me to post my problem to this list. OK, now for the problem: I
...
to convolve a Gaussian distribution with a binary pattern. For small
values
of the sigma of the Gaussian distribution the convolution returns an
array
of zeros. For a large value the results are OK.
I did some more research and found out that the zero array is returned if
the length of the Gaussian is smaller than the length of the binary
pattern. In the function call the Gaussian is the kernel and the binary
pattern is the data. The convolution mode is 'SAME'. I have swapped the
data and kernel in the convolve function call, but this has no influence
on
the result, as this is swapped again in convolve.py. A quick and dirty
workaround is to always make the Gaussian distribution longer than the
binary pattern, but for very large binary patterns this increases the
calculation time significantly. Does anyone have an idea how to solve
...
properly?
Met vriendelijke groeten,
Remco Jager
MAPPER Lithography
Lorentzweg 1
2628 CJ Delft, The Netherlands
tel.: +31 (0)15 2789439
fax: +31 (0)15-2789473
http://www.mapperlithography.com
This e-mail, attachments and (any part of) its content are (i) intended
for
the named addressee(s) only and (ii) strictly confidential and
Hi Remco,

Sounds like a bug. Which version of numarray do you use? Version 0.8 of
numarray should have appeared on sourceforge now. If the convolve in that
version does still not work, you could try out the convolution function in
the new nd_image package that is part of numarray 0.8. If that does not
work,
let me know since I am the author of that package, and will fix problems
with
it.

Cheers, Peter

On Monday 15 December 2003 11:24, R.Jager@mapperlithography.com wrote:
try
this
proprietary.
...
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Dr. Peter J. Verveer
Cell Biology and Cell Biophysics Programme
European Molecular Biology Laboratory
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Germany
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Re: [Numpy-discussion] Convolve returning zero array

R.Jager＠mapperlithography.com

Nadav Horesh

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