Mailman 3 January 2004 - SciPy-User

Representation of floating-point numbers
by Nils Wagner 15 Jan '04

15 Jan '04

Hi all, Python 2.3+ (#1, Sep 23 2003, 23:07:16) [GCC 3.3.1 (SuSE Linux)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> 5.1 5.0999999999999996 >>> What is the reason for this strange behavior ? GNU Octave, version 2.1.49 (i686-pc-linux-gnu). Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003 John W. Eaton. This is free software; see the source code for copying conditions. There is ABSOLUTELY NO WARRANTY; not even for MERCHANTIBILITY or FITNESS FOR A PARTICULAR PURPOSE. For details, type `warranty'. Please contribute if you find this software useful. For more information, visit http://www.octave.org/help-wanted.html Report bugs to <bug-octave(a)bevo.che.wisc.edu>. octave:1> format long octave:2> 5.1 ans = 5.10000000000000 Please can someone expand on the different behavior of python and octave. Nils

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Pythonw crashes if I try to plot Complex data points
by Hetal Patel 14 Jan '04

14 Jan '04

Whenever I try to plot complex data using either plt or gplt from any pyhton shell(Python,PythonWin,IDLE,PyCrust). windows reports that pythonw has crashed. I know that it's a bit unfair to ask the plot routines to plot complex data but I would expect an error, not python to crash. I'm running the latest SciPy release on Windows XP. Example code below crashes. >>>from scipy import * >>>a = arange(1,10,0.2) >>>b = a + 2.j >>>b array([ 1. +2.j, 1.2+2.j, 1.4+2.j, 1.6+2.j, 1.8+2.j, 2. +2.j, 2.2+2.j, 2.4+2.j, 2.6+2.j, 2.8+2.j, 3. +2.j, 3.2+2.j, 3.4+2.j, 3.6+2.j, 3.8+2.j, 4. +2.j, 4.2+2.j, 4.4+2.j, 4.6+2.j, 4.8+2.j, 5. +2.j, 5.2+2.j, 5.4+2.j, 5.6+2.j, 5.8+2.j, 6. +2.j, 6.2+2.j, 6.4+2.j, 6.6+2.j, 6.8+2.j, 7. +2.j, 7.2+2.j, 7.4+2.j, 7.6+2.j, 7.8+2.j, 8. +2.j, 8.2+2.j, 8.4+2.j, 8.6+2.j, 8.8+2.j, 9. +2.j, 9.2+2.j, 9.4+2.j, 9.6+2.j, 9.8+2.j]) >>>gplt.plot(b) At this point python\pythonw crashes with the following error "python.exe has encountered a problem and needs to close. We are sorry for the inconvenience." If anyone can help me resolve this then I would greatly appreciate it. _________________________________________________________________ Use MSN Messenger to send music and pics to your friends http://www.msn.co.uk/messenger

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Subdivision of an interval
by Nils Wagner 13 Jan '04

13 Jan '04

Hi all, How can I subdivide an interval provided that size(x) = n ? n = 10 h = (xu-xl)/n x = arange(xl,xu,h) Sometimes size(x) <> n Nils

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Interessant - und bei springeronline.com zu finden.
by nwagner＠mecha.uni-stuttgart.de 11 Jan '04

11 Jan '04

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I need help ! URGENT
by Rodrigo Vivi 08 Jan '04

08 Jan '04

I'm a brazilian researcher working in a governmental research center. I'm trying to use SciPy for the first time. This is the result: [vivi@lajinha vivi]$ python Python 2.3 (#2, Aug 31 2003, 17:27:29) [GCC 3.3.1 (Mandrake Linux 9.2 3.3.1-1mdk)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> from scipy import * /usr/lib/python2.3/site-packages/scipy_base/__init__.py:117: RuntimeWarning: Python C API version mismatch for module fastumath: This Python has API version 1012, module fastumath has version 1011. import fastumath # no need to use scipy_base.fastumath Segmentation fault [vivi@lajinha vivi]$ I Can't remove Python 2.3 and install Python 2.2. What can I do? __________________________________________ Rodrigo Vivi Computer Engeenier Cenpra - Centro de Pesquisas Renato Archer http://www.cenpra.gov.br __________________________________________

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weave and Differential Evolution ga code
by zunzun＠zunzun.com 06 Jan '04

06 Jan '04

I have used weave to inline my genetic algorithm code for Differential Evolution, and it is b-b-blazing fast. The DE home page is http://www.icsi.berkeley.edu/~storn/code.html which is chock full of source code. My native Python implementation crawls compared to any other language, but I do understand the algorithm now :) I'll put up the source code to my SciPy home page as soon as my membership stuff completes. James Phillips http://zunzun.com

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SciPy Installation
by Dr. Junbin Gao 04 Jan '04

04 Jan '04

Hi There I installed PyThon 2.2.3 on my D driver and downloaded sciPy SciPy-0.2.0_alpha_210.4077.win32-py2.2.exe <downloads/SciPy-0.2.0_alpha_210.4077.win32-py2.2.exe> But when I run the above exe file, I met the error message "Python version 2.2 required , which was not found in the registry" What does this mean?? Junbin Gao

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weave moved to scipy_core in CVS
by Pearu Peterson 04 Jan '04

04 Jan '04

Hi, weave module is now moved to scipy_core. This simplifies building scipy/chaco modules that need weave (that might not be installed when first checking out scipy/chaco modules). So, when updating scipy or chaco_all or any other CVS module that contained weave then you'll probably see the following message: cvs server: cannot open directory /home/cvsroot/world/scipy/Lib/weave: \ No such file or directory In that case you should remove your local copy of weave (or if you have made changes to local weave then make a backup) and re-run 'cvs update' or 'cvs co weave'. Regards, Pearu

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Simple least-squares curve fitting example
by scipy＠zunzun.com 03 Jan '04

03 Jan '04

Here is a linear least squares curvefitting example for the distribution if you would like to use it. James Phillips http://zunzun.com import scipy.linalg.basic xdata = [5.357, 5.457, 5.797, 5.936, 6.161, 6.697, 6.731, 6.775, 8.442, 9.769, 9.861] ydata = [0.376, 0.489, 0.874, 1.049, 1.327, 2.054, 2.077, 2.138, 4.744, 7.068, 7.104] matrix = [] for x in xdata: matrix.append([1.0, x, x*x]) # for y = a + bx + cx^2 coeffs = scipy.linalg.basic.lstsq(matrix, ydata)[0] print "scipy.linalg.basic.lstsq curve fitting example" print "fitting data to quadratic equation y = a + bx + cx^2" print "yields: x data y data calc value error" for i in range(len(xdata)): ycalc = coeffs[0] + coeffs[1] * xdata[i] + coeffs[2] * xdata[i] * xdata[i] error = ycalc - ydata[i] print " % .3f % .3f % .3f % .3f" % (xdata[i], ydata[i], ycalc, error) print

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