[Numpy-discussion] Convolve returning zero array

R.Jager at mapperlithography.com R.Jager at mapperlithography.com
Mon Dec 15 03:51:04 CST 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

MAPPER Lithography
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2628 CJ Delft, The Netherlands
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fax: +31 (0)15-2789473
http://www.mapperlithography.com

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|---------+---------------------------->
|         |           Peter Verveer    |
|         |           <verveer at embl-hei|
|         |           delberg.de>      |
|         |                            |
|         |           15/12/2003 12:04 |
|         |                            |
|---------+---------------------------->
  >------------------------------------------------------------------------------------------------------------------------------|
  |                                                                                                                              |
  |       To:       R.Jager at mapperlithography.com, numpy-discussion at lists.sourceforge.net                                        |
  |       cc:                                                                                                                    |
  |       Subject:  Re: [Numpy-discussion] Convolve returning zero array                                                         |
  >------------------------------------------------------------------------------------------------------------------------------|




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 at mapperlithography.com wrote:
> 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
try
> 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
this
> 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
proprietary.
> All rights are reserved by MAPPER Lithography. Any unauthorized use,
> disclosure and/or copying are strictly prohibited, except with prior and
> express written permission by MAPPER Lithography. Should you have
received
> this e-mail, attachments and its content by mistake, please bring this to
> our attention and destroy this e-mail and attachments in full. Thank you.
>
>
>
>
>
>
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--
Dr. Peter J. Verveer
Cell Biology and Cell Biophysics Programme
European Molecular Biology Laboratory
Meyerhofstrasse 1
D-69117 Heidelberg
Germany
Tel. : +49 6221 387245
Fax  : +49 6221 387306












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