On Thu, Aug 13, 2020 at 11:17:00PM +0100, Stefano Borini wrote:
> The math module has plenty of mathematical functions that are very
> interesting, but no Matrix object.
Funny you mention this, I have been working on a Matrix object for
precisely the use-case you discuss (secondary school maths), where
performance is not critical and the dimensions of the matrix is
typically single digits.
I, um, got distracted with some over-engineering and then distracted
further by work and life, but perhaps this is a good opportunity for me
to get it back on track.
> Generally, when a Matrix object is needed, numpy is the point of
> reference, but numpy requires understanding pip, installing modules,
> maybe creating a virtual environment and finally understanding numpy.
And numpy also offers a surprising interface that doesn't match
matrices. (Well, surprising to those who aren't heavy users of numpy :-)
py> A = numpy.array([[1, 2], [3, 4]])
py> A*A
array([[ 1, 4],
[ 9, 16]])
To get *matrix multiplication* you have to use the `@` multiplication
operator from PEP 465:
py> A@A
array([[ 7, 10],
[15, 22]])
https://www.python.org/dev/peps/pep-0465/
But what's really surprising about numpy arrays is broadcasting:
py> A = numpy.array([[1, 2], [3, 4]])
py> B = numpy.array([[10, 20]])
py> A + B
array([[11, 22],
[13, 24]])
I don't know if broadcasting is actually useful or not, but
it's not what you want when doing matrix arithmetic at a
secondary school level.
--
Steven
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