Mailman 3 May 2004 - NumPy-Discussion

puzzling compiler warning for numeric extension
by Russell E Owen May 13, 2004

May 13, 2004

I modified an existing numeric c extension today, adding a function that returns a new array. This is the first time I've used NA_NewArray. The code seems to run fine, but I get a disturbing compiler warning: [rowen:Shared Files/Guider/PyGuide] rowen% python setup.py build ... src/radProfModule.c: In function `Py_radSqByRadInd': src/radProfModule.c:378: warning: return from incompatible pointer type The associated code can be summarized as follows (and it is simple enough that I've also appended a copy). The error is thrown on the last line: static PyObject *Py_radSqByRadInd(PyObject *self, PyObject *args) { long nElt; Long *radSqByRadInd; if (!PyArg_ParseTuple(args, "l", &nElt)) return NULL; ... return NA_NewArray((void *)radSqByRadInd, tLong, 1, nElt); } So...am I actually doing something wrong, or is this warning normal? -- Russell P.S. the full code: static PyObject *Py_radSqByRadInd(PyObject *self, PyObject *args) { long nElt; Long radInd; char ModName[] = "radSqByRadInd"; Long *radSqByRadInd; if (!PyArg_ParseTuple(args, "l", &nElt)) return NULL; if (nElt < 0) { PyErr_Format(PyExc_ValueError, "%s: nPts < 0", ModName); return NULL; } // allocate max(3, nElt) elements (simplifies the computation // and avoids calling calloc on 0 elements) radSqByRadInd = calloc(MAX(nElt, 3), sizeof *radSqByRadInd); if (radSqByRadInd == NULL) { PyErr_Format(PyExc_MemoryError, "%s: insufficient memory", ModName); return NULL; } for (radInd=0; radInd<3; radInd++) { radSqByRadInd[radInd] = radInd; } for (radInd=3; radInd<nElt; radInd++) { radSqByRadInd[radInd] = (radInd - 1) * (radInd - 1); } return NA_NewArray((void *)radSqByRadInd, tLong, 1, nElt); }

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Question about complex variables
by Karthikesh Raju May 12, 2004

May 12, 2004

Hi All, i found something strange about complex matrices/arrays. Is it true that transposing them does not yeald the mathematically correct transpose (the signs of the imaginary part is reversed)? This leads to wrong results while calculating covariances etc .. Actually i find that things go a bit wild with complex number, is it true? Warm regards karthik ----------------------------------------------------------------------- Karthikesh Raju, email: karthik(a)james.hut.fi Researcher, http://www.cis.hut.fi/karthik Helsinki University of Technology, Tel: +358-9-451 5389 Laboratory of Comp. & Info. Sc., Fax: +358-9-451 3277 Department of Computer Sc., P.O Box 5400, FIN 02015 HUT, Espoo, FINLAND -----------------------------------------------------------------------

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add.reduce for character arrays
by Faheem Mitha May 10, 2004

May 10, 2004

Hi, The following does not work. I am trying to do something similar to add.reduce, except that I want strings concatenated across the appropriate axes. I was hoping that Python would "magically" recognise that addition in strings translated to concatenation. Incidentally, the error message is not terribly imformative. Is there any way to make this work, or any other method people can suggest, or do I need to write my own function? Thanks. Regards, Faheem. ********************************************************************** In [43]: s Out[43]: CharArray([['a', 'b', 'c'], ['d', 'e', 'f'], ['g', 'h', 'i']]) In [44]: numarray.add.reduce(s,1) --------------------------------------------------------------------------- error Traceback (most recent call last) /home/faheem/wc/corrmodel/boost/<console> error: getShape: sequence object nested more than MAXDIM

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Announce: ErrorVal.py 1.0 for error-bounds calculations
by Gary Ruben May 9, 2004

May 9, 2004

I finally got around to putting my errorbar calculation module on my website. <http://users.bigpond.net.au/gazzar/python.html> This should be of interest to Numeric Python users who deal with calculation of error-bounds on experimental data. Synopsis: A module providing a Python number type class and helper functions to ease the task of computing error bounds on experimental data values. This module defines an abstract data type, Err, which carries a central/prime value and upper and lower error bounds. Helper functions are provided to allow Python Numeric rank-1 arrays of Err objects to be constructed with ease and to apply Numeric Ufuncs. Written under Python 2.3.3 and Numeric 23.0 Example of usage: upperPressure = ArrayOfErr([909., 802., 677., 585., 560., 548.], 1.0) lowerPressure = ArrayOfErr([144., 246., 378., 469., 493., 505.], 1.0) pressureDiff = upperPressure - lowerPressure V_RStandard = ArrayOfErr([2.016, 2.016, 2.020, 2.017, 2.021, 2.019], 0.001) R = 100.2 # standard resistor value [Ohm] I = V_RStandard / R # current [A] V_RAB = ArrayOfErr([6.167, 6.168, 6.170, 6.160, (6.153, 0.02), (5.894, 0.01)], 0.002) R_AB = V_RAB / I logR_AB = ApplyUfuncToErr(R_AB, log10) # This means log10(R_AB) print PrimeVals(logR_AB) print MinVals(logR_AB) print MaxVals(logR_AB) Enjoy, Gary Ruben -- ___________________________________________________________ Sign-up for Ads Free at Mail.com http://promo.mail.com/adsfreejump.htm

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numarraycore
by Colin J. Williams May 7, 2004

May 7, 2004

It would help to have some documentation on the purpose and usage of the class UsesOpPriority and its variable op_priority.

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covariance and other linear algebra functions
by Karthikesh Raju May 7, 2004

May 7, 2004

Hi, Is am searching for a covariance function and other linear algebra functions like eigen value decomposition. i am interested in both scipy (havent managed to get scipy installed on the main computation systems) and also numarray solution. With warm regards karthik ----------------------------------------------------------------------- Karthikesh Raju, email: karthik(a)james.hut.fi Researcher, http://www.cis.hut.fi/karthik Helsinki University of Technology, Tel: +358-9-451 5389 Laboratory of Comp. & Info. Sc., Fax: +358-9-451 3277 Department of Computer Sc., P.O Box 5400, FIN 02015 HUT, Espoo, FINLAND -----------------------------------------------------------------------

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ANN: SciPy 2004 Conference - Python for Scientific Computing
by Travis N. Vaught May 6, 2004

May 6, 2004

Greetings, The 1st annual *SciPy Conference* will be held this year at Caltech, September 2-3, 2004. As some of you may know, we've experienced great participation in two SciPy "Workshops" (with ~70 attendees in both 2002 and 2003) and this year we're graduating to a "conference." With the prestige of a conference comes the responsibility of a keynote address. This year, Jim Hugunin has answered the call and will be speaking to kickoff the meeting on Thursday September 2nd. Jim is the creator of Numeric Python, Jython, and co-designer of AspectJ. Jim is currently working on IronPython--a fast implementation of Python for .NET and Mono. Registration is now open. More information can be found here: http://www.scipy.org/wikis/scipy04 You may register early online for $100.00. Registration includes breakfast and lunch Thursday & Friday and a very nice dinner Thursday night. After July 16, registration will cost $150.00. Call for Presenters: If you are interested in presenting at the conference, you may submit an abstract in Plain Text, PDF or MS Word formats to abstracts(a)scipy.org -- the deadline for abstract submission is July 1, 2004. Papers and/or presentation slides are acceptable and are due by August 20, 2004. We're also planning three days of informal "Coding Sprints" prior to the conference -- August 30 to September 1, 2004. Conference registration is not required to participate in the sprints. Please email the list, however, if you plan to attend. Topics for these sprints will be determined via the mailing lists as well, so please submit any suggestions for topics to the scipy-user 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. I look forward to seeing you at the conference. Best Regards, Travis N. Vaught

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