Mailman 3 July 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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Triangulation of L-shaped domains
by Nils Wagner Sept. 6, 2006

Sept. 6, 2006

Hi all, I have installed delaunay from the sandbox. How can I triangulate L-shaped domains ? My first try is somewhat unsatisfactory (delaunay.png) ? How can I remove the unwanted triangles down to the right ? Nils

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numpy netcdf reader
by Rob Hetland Aug. 18, 2006

Aug. 18, 2006

Konrad & scipy-users, I have made some changes to the scipy.sandbox.netcdf package so that it installs correctly. (I am a total hack at distutils, but it seems to do the right thing..). This could also be installed as a stand alone package, since it does not actually depend on scipy for anything. I have tested this module on my Mac, a Redhat distribution, and a Win box (using cygwin netcdf libraries), and all seem to work fine. One issue I have is that I can't seem to write a single character. In one of the programs I use, a variable called 'sherical' is expected to have a value of 'T' or 'F'. I am unable to write a value to this variable no matter what I try. Similar zero-dimensional assignments work for floating point numbers, just not for characters. Any advice? -Rob ---- Rob Hetland, Assistant Professor Dept. of Oceanography, Texas A&M University http://pong.tamue.edu/~rob phone: 979-458-0096, fax: 979-845-6331

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sorry (mailing list is a bit slow?)
by David Grant Aug. 10, 2006

Aug. 10, 2006

Sorry for the re-send everybody (and for this message). It looks like my first email and the re-send hit the archives already but I have yet to receive either of them through the mailing list. Did anyone receive either of those messages? Please reply in private, do not reply to the list. Thanks and sorry again. -- David Grant

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jn & lpmn or sph_jn...
by fred Aug. 4, 2006

Aug. 4, 2006

Hi, I like how jn works because I can array as arg (I use jn on 3D array). This is not the case for sph_jn & lpmn :-( I tried to bypass it, with something like def foo(m,n): x = arange(0,Lx,dx) y = arange(0,Ly,dy) z = arange(0,Lz,dz) tab = zeros((len(x), len(y), len(z)), dtype='f') for i in range(0,len(x)): for j in range(0,len(y)): for k in range(0,len(z)): tab[i,j,k] = cos(theta(x[i],y[j],z[k])) # tab[i,j,k] = Ymn_theta_p(x[i],y[j],z[k],m,n)*sph_jn(n,r(x[i],y[j],z[k]))[n][0]*rho(x[i],y[j],z[k]) return (tab) but knowing my arrays have more than hundred of thousand cells, it is _very_ slow. I guess sph_jn & lpmn are written like this because they return arrays (0 to n order, derivative, etc). I wish to have Legendre & spherical Bessel functions which could accept array as arg. I only need the last order (n) and the derivative (which could be called by another func) for the same order. How could I write this ? Or is there another way to do the same thing ? Ex. : In [1]: from scipy.special import * In [2]: x=arange(0,1,0.1) In [3]: print jn(1,x) [ 0. 0.04993753 0.09950083 0.14831882 0.19602658 0.24226846 0.28670099 0.32899574 0.36884205 0.40594955] In [4]: print sph_jn(1,x) --------------------------------------------------------------------------- exceptions.ValueError Traceback (most recent call last) /home/fred/<ipython console> /usr/local/lib/python2.4/site-packages/scipy/special/basic.py in sph_jn(n, z) 212 """ 213 if not (isscalar(n) and isscalar(z)): --> 214 raise ValueError, "arguments must be scalars." 215 if (n!= floor(n)) or (n<0): 216 raise ValueError, "n must be a non-negative integer." ValueError: arguments must be scalars. Cheers, -- Fred.

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Mesh generator
by Nils Wagner Aug. 4, 2006

Aug. 4, 2006

Hi all, Is there something similar available for scipy ? http://www-math.mit.edu/~persson/mesh/ Nils

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scipy 0.4.9/numpy 0.9.8 & jn_zeros()
by fred Aug. 3, 2006

Aug. 3, 2006

Hi all, Since the new release, I get this error message : Python 2.4.3 (#1, Jul 25 2006, 18:55:45) [GCC 3.3.5 (Debian 1:3.3.5-13)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> from scipy.special.basic import jn_zeros >>> print jn_zeros(0,1) Floating exception What am I doing wrong ? Cheers, -- Fred.

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Problem with AstroLib - coords-0.2
by Tara Murphy Aug. 2, 2006

Aug. 2, 2006

Hi, I've just started playing around with coords-0.2 and am having a problem reproducing the example shown on the wiki: http://www.scipy.org/AstroLibCoordsSnapshot I am using Python2.4 and I've pasted my session below. When I try ob.dd() and ob.j2000() the answers are not the same: >>> import coords as C >>> ob=C.Position('12:34:45.34 -23:42:32.6') >>> ob.hmsdms() '12:34:45.340 -23:42:32.600' >>> ob.dd() (188.68891666666667, -23.709055555555555) >>> ob.j2000() (-171.31108333333333, -23.709055555555555) Is this something I'm misinterpreting, or is it a bug? thanks, Tara ----- Dr. Tara Murphy ARC Postdoctoral Fellow School of IT | School of Physics Room 448 | Room 565 University of Sydney | University of Sydney P: +61 2 9351 4723 | P: +61 2 9351 3041 E: tm(a)it.usyd.edu.au | E: tara(a)physics.usyd.edu.au http://www.it.usyd.edu.au/~info1903

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