Mailman 3 October 2006 - SciPy-User

Help required regding Eigenvectors
by Sudheer Phani March 14, 2022

March 14, 2022

Hello All, I have been encountering some strange problems with the calculation of eigen vectors using python. The problem is with the sign of the eigen vectors calculated. On Very few occasions the eigen vectors calculated using python have an opposite sign than the actual eigenvectors, though the magnitude is correct. Can any one of you plz help me in this regard and suggest me some solution if you have encoutered similar problems . Any help in this regd is appreciated Thanks in Advace regds Sudheer

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3D plotting
by Robert Cimrman Sept. 10, 2009

Sept. 10, 2009

Hi, I need to do some simple 3D plots, so I tried the two Cookbook recipes (xplt, mplot3d) and failed: * xplt: does not work when using a custom installation directory such as python setup.py install --root=/home/share/software apparently the gistdata directory path is wrong: gist.error: failed to create drawing -- Gist work.gs style sheet missing * mplot3d: does not work with my version of matplotlib (0.80). I have made the changes mentioned in the Cookbook to no avail. (Axes.__init__() args apparently changed, as well as some other matplotlib object attributes) Any ideas? mplot3d looks great, I would really like to use it! thanks, r.

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FAIL: check_dot (scipy.linalg.tests.test_blas.test_fblas1_simple)
by Andrew Jaffe Nov. 16, 2006

Nov. 16, 2006

Hi All- I get the following error with scipy.__version__ = '0.5.0.2121' on PPC OSX 2.4.3 Universal Build with numpy 1.0.2889 (note that the latter has a known longdouble problem, but I don't think that's related). Indeed the fblas complex [c,z]dot[c,u] functions do seem to fail. (In fact, zdotc([1,-4,3],[2,3,1]) hangs the interpreter...) Andrew ====================================================================== FAIL: check_dot (scipy.linalg.tests.test_blas.test_fblas1_simple) ---------------------------------------------------------------------- Traceback (most recent call last): File "/Library/Frameworks/Python.framework/Versions/2.4/lib/python2.4/site-packages/scipy-0.5.0.2121-py2.4-macosx-10.3-fat.egg/scipy/linalg/tests/test_blas.py", line 75, in check_dot assert_almost_equal(f([3j,-4,3-4j],[2,3,1]),-9+2j) File "/Library/Frameworks/Python.framework/Versions/2.4/lib/python2.4/site-packages/numpy-1.0.2889-py2.4-macosx-10.3-fat.egg/numpy/testing/utils.py", line 156, in assert_almost_equal assert round(abs(desired - actual),decimal) == 0, msg AssertionError: Items are not equal: ACTUAL: (-1.9980511665344238+2.1130658899732593e-36j) DESIRED: (-9+2j) ====================================================================== FAIL: check_dot (scipy.lib.tests.test_blas.test_fblas1_simple) ---------------------------------------------------------------------- Traceback (most recent call last): File "/Library/Frameworks/Python.framework/Versions/2.4/lib/python2.4/site-packages/scipy-0.5.0.2121-py2.4-macosx-10.3-fat.egg/scipy/lib/blas/tests/test_blas.py", line 76, in check_dot assert_almost_equal(f([3j,-4,3-4j],[2,3,1]),-9+2j) File "/Library/Frameworks/Python.framework/Versions/2.4/lib/python2.4/site-packages/numpy-1.0.2889-py2.4-macosx-10.3-fat.egg/numpy/testing/utils.py", line 156, in assert_almost_equal assert round(abs(desired - actual),decimal) == 0, msg AssertionError: Items are not equal: ACTUAL: (-1.9980511665344238+2.1996782422872647e-36j) DESIRED: (-9+2j)

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Parallel OO programming in Python.
by fiepye＠atlas.cz Nov. 6, 2006

Nov. 6, 2006

Hello. I am interested in parallel computing in Python. Except other modules I would like to use new modules for vector and matrix operations and scientific computing SciPy and NumPy. I have already installed LAPACK and BLAS libraries. It works well. For object oriented parallel programming in Python on a single machine I can use techniques such as Bulk Synchronous Parallelism (BSP) or Message Passing Interface (MPI). There are mentioned some modules and packages for Python on http://www.scipy.org/Topical_Software Article: Parallel and distributed programming. After reading prerequisites and limitations I thing that the following ones could be good for me: PyMPI Pypar MPI for Python But I can't distinguish which one brings fewer limitations, is efficient in application and will develop in future. My favorite is BSP, but I can't find a package for present SciPy and NumPy. Could anybody give me a recommendation, which way I should go. Thanks. Fie Pye --------------------------------------- Máme další spot P.Čtvrtníčka. Podívejte se www.neuservis.cz

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image processing
by Vicent Mas (V+) Nov. 3, 2006

Nov. 3, 2006

Hello, I'm a newcomer to process image and scipy. I'm trying to process a binary image in order to get the biggest connected component. In matlab one can use the bwareaopen to achieve this goal but I don't know how to do it with scipy. I've been looking at scipy.ndimage module with no luck. Could you help me, please? Thanks in advance. -- :: \ / Vicent Mas http://www.carabos.com 0;0 / \ Cárabos Coop. Enjoy Data V V " "

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wiki
by fred Nov. 3, 2006

Nov. 3, 2006

Hi the list, Only two shorts question: 1) How can I add a page ? I want to add Cookbook/MayaVi/InstallPythonStuffFromSource page. 2) How can I delete some png image files previously uploaded ? Thanks in advance. Cheers, -- http://scipy.org/FredericPetit

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csr_matrix
by Sam frizou Nov. 2, 2006

Nov. 2, 2006

Hi, Is it possible to get the set of indices of non null elements of a sparse matrix M ? I means I can see them by doing "print M", but I want to use them, so I would like something like a list of (i,j). Thanks. -- On obtient beaucoup plus avec un mot gentil et une arme qu'avec seulement un mot gentil - "Al Capone".

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pyaudio 0.3, with docs !
by David Cournapeau Nov. 2, 2006

Nov. 2, 2006

Hi, I improved pyaudio last WE using indications given by various people on the list or privately, and as I finally got the motivation to set-up something which looks like a webpage, there is a doc with examples which show how to use it. The API to open files for writing is much saner, and the setup.py should be smart enough to grab all informations necessary to the wrapper, including the location of the shared libsndfile: download: http://www.ar.media.kyoto-u.ac.jp/members/david/softwares/pyaudio/#installa… doc + examples: http://www.ar.media.kyoto-u.ac.jp/members/david/softwares/pyaudio/ I would appreciate to hear reports on platforms which are not linux (windows, mac os X) to see if my the setup.py works there, Cheers, David

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Need more comments from scientific community on python-dev
by Travis Oliphant Nov. 1, 2006

Nov. 1, 2006

I'm recruiting more comments on python-dev regarding my two proposals for improving Python's native ability to share ndarray-like information. There is a dearth of scientific-computing and number-crunching-aware people on python-dev. The result is that I sound like a lone voice arguing for something that nobody cares about. When, I don't think that is true. Please, please. If you want Python to grow support for the array interface (or something like it), then please speak up on python-dev. Even something as simple as I really see the need for a way to exchange data-format information between two objects sharing the buffer protocol can be helpful. You can post through the gmane newsgroup interface: gmane.comp.python.devel Find any of the posts on the PEP's I've introduced. Thanks for your help. -Travis

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scipy 0.5.1 and numpy 1.0
by Souheil Inati Oct. 31, 2006

Oct. 31, 2006

Checking the website here http://www.scipy.org/Download, it is unclear if the latest stable release of SciPy (0.5.1) is compatible with the latest stable release of (NumPy 1.0). Could someone please clarify this for me. Thanks, Souheil

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