Mailman 3 June 2005 - SciPy-User

Help required regding Eigenvectors
by Sudheer Phani 14 Mar '22

14 Mar '22

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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Plotting Question
by CJ Fleck 01 Jul '05

01 Jul '05

Using the gnuplot module to plot data, is it possible to plot functions? That is, can I plot x**2 somehow? If so, how?

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Fitting a polynomial to data
by CJ Fleck 30 Jun '05

30 Jun '05

I have some data points that I'd like to fit a polynomial to. I have a gut feeling that this can be done with scipy, but I'm not sure how. Admitadly, my math skills are a bit lacking and I'm not real sure how to go about it. If anyone can point me in the right direction or give me examples on how to do this, it would be much appreciated. CJ

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Installing Scipy on Mac os X Panther G5
by rajb 30 Jun '05

30 Jun '05

Hi I'm trying to install SciPy on a G5 running Mac OS X Panther with Nagware f95 compiler. the build terminates with the following ------------------------------------------------------------------------ ------------------- compiling Fortran sources f95(f77) options: '-fixed -O4' f95(f90) options: '-O4' f95(fix) options: '-fixed -O4' compile options: '-c' f95:f77: Lib/special/mach/r1mach.f -c option specified twice, continuing Note: On some machines, -ieee=full may be needed for best performance Obsolescent: Lib/special/mach/r1mach.f, line 1: Fixed source form Error: Lib/special/mach/r1mach.f, line 173: Inconsistent structure for arg 1 in call to I1MCRA [f95 error termination] -c option specified twice, continuing Note: On some machines, -ieee=full may be needed for best performance Obsolescent: Lib/special/mach/r1mach.f, line 1: Fixed source form Error: Lib/special/mach/r1mach.f, line 173: Inconsistent structure for arg 1 in call to I1MCRA [f95 error termination] error: Command "f95 -fixed -O4 -c -c Lib/special/mach/r1mach.f -o build/temp.darwin-7.9.0-Power_Macintosh-2.4/Lib/special/mach/ r1mach.o" failed with exit status 2 ------------------------------------------------------------------------ ------------------- Does anyone know what's happening? Thanks Raj

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do complex numbers default to double precision?
by Ryan Krauss 30 Jun '05

30 Jun '05

I have a matrix that is a function of a complex valued input. I am trying to find that value of that input that drives the determinant of the matrix to zero. I am searching for this value using fmin. The error I am trying to minimize is the abs(det(complex matrix)). I don't seem to be able to drive this error lower that roughly 9e-17, regardless of the values for ftol and xtol I use. Am I hitting some internal limitation? Are complex values by default single or double precision? Thanks, Ryan

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'linear regression'
by Christian Meesters 30 Jun '05

30 Jun '05

Hi I'm wondering whether there is a tool in scipy which can do a line fit ('linear regression') fit for me. (Preferably something which can work with and without given error arrays in x and/or y.) Else I'd have to code it myself ... Well, I couldn't find such a function described in the manual: Could anyone pleas point it out to me where I can find this in scipy - in case it really exists? Thanks, Christian

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null space of a matrix
by Ryan Krauss 29 Jun '05

29 Jun '05

This is probably a Numeric question, but is there an easy way to find the null space of a matrix in SciPy? Ryan

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ANN: SciPy 2005 Conference - Python for Scientific Computing
by Janet M. Swisher 29 Jun '05

29 Jun '05

Greetings, The 2nd annual *SciPy Conference* on Python for Scientific Computing will be held again this year at Caltech, September 22-23, 2005. History: -------- This event started as SciPy "Workshops" held in 2002 and 2003, with great participation by the ~70 people attending. In 2004, it became a "conference", with attendance jumping to 87 participants. Registration: ------------- Registration is now open. More information can be found here: http://www.scipy.org/wikis/scipy05 You may register early online for $100.00. Registration includes breakfast and lunch Thursday & Friday and a very nice dinner Thursday night. After July 29, registration will cost $150.00. Call for Presenters: -------------------- If you are interested in presenting at the conference, you can submit an abstract in Plain Text, PDF or MS Word formats to abstracts(a)scipy.org -- the deadline for abstract submission is July 29, 2005. Papers or presentation slides are acceptable and are due by August 26, 2005. Feedback: --------- If you have any feedback from last year's conference or suggestions for this year, please discuss via the scipy mailing list: list signup: http://www.scipy.org/mailinglists/ list address: scipy-user(a)scipy.org Please forward this announcement to anyone/list that might be interested. Best Regards, -- Janet Swisher --- Senior Technical Writer Enthought, Inc. http://www.enthought.com

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chi square value on leastsq
by Fernando Avila Castro 29 Jun '05

29 Jun '05

Hi, i'm using leastsq to fit a set of data and it works quite well. However, i would like to get the chi square value of this fit, or at least any indication of how good the fit was. Thanks.

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Bug(?) in optimize.fmin_ncg
by Nils Wagner 29 Jun '05

29 Jun '05

Hi all, I have obtained a runtime error depending on the order n. The test program is attached. It works fine for n = 10 Optimization terminated successfully. Current function value: 0.022338 Iterations: 7 Function evaluations: 8 Gradient evaluations: 69 Hessian evaluations: 0 fmin_ncg 8 Approximated smallest eigenvalue 0.0223383475497 smallest eigenvalue by linalg.eigvals 0.0223383475497 Any idea how to fix this problem would be appreciated. Thanks in advance. Nils numerix Numeric 24.0b2 Traceback (most recent call last): File "ncg.py", line 25, in ? xopt4 = optimize.fmin_ncg(func,x0, fprime) File "/usr/lib/python2.3/site-packages/scipy/optimize/optimize.py", line 978, in fmin_ncg xsupi = xsupi + dri0/curv * psupi ZeroDivisionError: float division

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