Hello, Sorry to disturb again, but the topic still bugs me somehow... I'll try to rephrase the question:
- What's the influence of the type of N-array representation with respect to TENSOR-calculus? - Are multiple representations possible? - I assume that the order of the dimensions plays a major role in for example TENSOR product. Is this assumption correct? As I said before, my math skills are lacking in this area... I hope you consider this a valid question. kind regards, Dieter On Fri, Jan 30, 2015 at 2:32 AM, Alexander Belopolsky <ndar...@mac.com> wrote: > > On Mon, Jan 26, 2015 at 6:06 AM, Dieter Van Eessen < > dieter.van.ees...@gmail.com> wrote: > >> I've read that numpy.array isn't arranged according to the >> 'right-hand-rule' (right-hand-rule => thumb = +x; index finger = +y, bend >> middle finder = +z). This is also confirmed by an old message I dug up from >> the mailing list archives. (see message below) >> > > Dieter, > > It looks like you are confusing dimensionality of the array with the > dimensionality of a vector that it might store. If you are interested in > using numpy for 3D modeling, you will likely only encounter 1-dimensional > arrays (vectors) of size 3 and 2-dimensional arrays (matrices) of size 9 > or shape (3, 3). > > A 3-dimensional array is a stack of matrices and the 'right-hand-rule' > does not really apply. The notion of C/F-contiguous deals with the order > of axes (e.g. width first or depth first) while the right-hand-rule is > about the direction of the axes (if you "flip" the middle finger right hand > becomes left.) In the case of arrays this would probably correspond to > little-endian vs. big-endian: is a[0] stored at a higher or lower address > than a[1]. However, whatever the answer to this question is for a > particular system, it is the same for all axes in the array, so right-hand > - left-hand distinction does not apply. > > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > http://mail.scipy.org/mailman/listinfo/numpy-discussion > > -- gtz, Dieter VE
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