Mailman 3 June 2007 - NumPy-Discussion

flatindex
by Tobias Knopp June 1, 2007

June 1, 2007

Hi! I was looking for a method to find the indices of the smallest element of an 3-dimensional array a. Therefore i used a.argmax() The problem was, that argmax gives me a flat index. My question is, if there is a build-in function to convert the flat index back to a multidimensional one. I know how to write such a procedure but was curious if one exists in numpy. Thanks for response and the really impressive software package. Tobi

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ATLAS,LAPACK compilation - help!
by sittner＠lkb.ens.fr May 31, 2007

May 31, 2007

Hello there, I'm new here, so excuse me if the solution is trivial: i have installed ATLAS and LAPACK on my ubuntu 7 dual core intel machine. now, when i try to install numpy, it tells me it doesn't find these libraries: " $ python setup.py install Running from numpy source directory. F2PY Version 2_3816 blas_opt_info: blas_mkl_info: libraries mkl,vml,guide not found in /usr/local/lib libraries mkl,vml,guide not found in /usr/lib NOT AVAILABLE atlas_blas_threads_info: Setting PTATLAS=ATLAS libraries lapack,blas not found in /usr/local/lib/ATLAS/src/ libraries lapack,blas not found in /usr/local/lib/ATLAS libraries lapack,blas not found in /usr/local/lib libraries lapack,blas not found in /usr/lib NOT AVAILABLE atlas_blas_info: libraries lapack,blas not found in /usr/local/lib/ATLAS/src/ libraries lapack,blas not found in /usr/local/lib/ATLAS libraries lapack,blas not found in /usr/local/lib libraries lapack,blas not found in /usr/lib NOT AVAILABLE ......" I have installed ATLAS and lapack with no errors. ATLAS is in usr/local/lib/ATLAS/: $ ls /usr/local/lib/ATLAS bin doc interfaces Make.Linux_UNKNOWNSSE2_2 README tune CONFIG include lib makes src config.c INSTALL.txt Makefile Make.top tst.o so, what seems to be the problem? thanks, t

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numpy.distutils, system_info and dll/exp/lib
by David Cournapeau May 31, 2007

May 31, 2007

Hi, In one of my package, I use numpy.distutils.system_info to detect a C library. This works well on linux and Mac OS X, but on windows, the library is not detected if only the dll is present. If the .lib is there, then it is detected; the dll itself works OK (I can use it from ctypes normally). Am I doing something wrong in my configuration ? """ class SndfileNotFoundError(NotFoundError): """ sndfile (http://www.mega-nerd.com/libsndfile/) library not found. Directories to search for the libraries can be specified in the site.cfg file (section [sndfile]).""" class sndfile_info(system_info): #variables to override section = 'sndfile' notfounderror = SndfileNotFoundError libname = 'sndfile' header = 'sndfile.h' def __init__(self): system_info.__init__(self) def calc_info(self): """ Compute the informations of the library """ prefix = 'lib' # Look for the shared library sndfile_libs = self.get_libs('sndfile_libs', self.libname) lib_dirs = self.get_lib_dirs() for i in lib_dirs: tmp = self.check_libs(i, sndfile_libs) if tmp is not None: info = tmp break #else: # raise self.notfounderror() # Look for the header file include_dirs = self.get_include_dirs() inc_dir = None for d in include_dirs: p = self.combine_paths(d,self.header) if p: inc_dir = os.path.dirname(p[0]) headername = os.path.abspath(p[0]) break if inc_dir is not None and tmp is not None: if sys.platform == 'win32': # win32 case fullname = prefix + tmp['libraries'][0] + \ '.dll' elif sys.platform == 'darwin': # Mac Os X case fullname = prefix + tmp['libraries'][0] + '.' + \ str(SNDFILE_MAJ_VERSION) + '.dylib' else: # All others (Linux for sure; what about solaris) ? fullname = prefix + tmp['libraries'][0] + '.so' + \ '.' + str(SNDFILE_MAJ_VERSION) fullname = os.path.join(info['library_dirs'][0], fullname) dict_append(info, include_dirs=[inc_dir], fullheadloc = headername, fulllibloc = fullname) else: return #print self self.set_info(**info) return """ The problem is, the library I am using is distributed only as a dll, not with the .lib. Right now, users of my package need to generate the .lib by themselves from the dll, using visual studio compiler, which is really too much (specially since the library itself is fine; using the compiler is necessary only for distutils to find the library !). cheers, David

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GPU implementation?
by Martin Ünsal May 31, 2007

May 31, 2007

I was wondering if anyone has thought about accelerating NumPy with a GPU. For example nVidia's CUDA SDK provides a feasible way to offload vector math onto the very fast SIMD processors available on the GPU. Currently GPUs primarily support single precision floats and are not IEEE compliant, but still could be useful for some applications. If there turns out to be a significant speedup over using the CPU, this could be a very accessible way to do scientific and numerical computation using GPUs, much easier than coding directly to the GPU APIs. Martin

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