John Fredsted

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18 years, 261 days

MaplePrimes Activity

These are questions asked by John Fredsted

Consider the following Matrix constructor:

M := Matrix(3,(i,j) -> a||i||j + I*b||i||j,shape = hermitian);

It generates the following output:

That appears to me to be definitely wrong, a hermitian matrix allowing nonzero real-valued diagonal elements (otherwise quantum mechanics would be a rather vacuous theory). For shape = antihermitian, the diagonal still contains only zeros, even though it should contain nonzero purely complex-imaginary elements. Have I fundamentally misunderstood something?

PS: I was aware of this shortcoming back in Maple 9.5 (the previous version I have been working with), there manually circumventing it, but I certainly expected that it had been fixed since then.

Is it just me that is being daft, or am I correct in ascerting that there does still not exist (even in Maple 17) a command for taking the commutator of two matrices?

As far as I can tell from the help pages, there exists only a commutator of vector fields (in the tensor package), and a commutator af algebraic quantities (in the Physics package).

Not having such a command for matrices is, of course, not critical, as it is very easily programmed, but I am just surprised, for something as fundamental as checking some representation of a Lie algebra, say, requires taking such commutators.

Due to the seemingly persistent tabbing-problem, I would like to learn how to work with Maple using an external editor: If I could recreate my packages using an external editor, thereby avoiding both the tabbing-issue and the blowup associated with what I call the 'XML-contamination of documents', and from them create the associated libraries, then I would be satisfied. For then I would use only a single document in Maple worksheet mode as a front end. Therefore:

Can anyone point me to some information concerning 1.) choice of an editor, and 2.) how to use an external editor to create packages and libraries in Maple?

Some three and a half years ago, after having upgraded from Maple 9.5 to Maple 11, I had to abandon the latter and return to the former, the problem being that the GUI did not allow me something as completely trivial as to go to the very end of a line by pressing END on my keyboard, see I declare defeat: rolling back to Maple 9.5.

With Microsoft phasing out updates for Windows XP as of April 2014, I decided to run Windows 7 instead of XP. According to MapleSoft, Maple 9.5 does not run under either 32 bit or 64 bit Windows 7, and thus I was forced to upgrade Maple.

Having installed Maple 17 an hour or so ago, I decided to open a Maple 9.5 document to see how it was rendered. To my complete surprise I found again that I was not able to move to the very end of a line using END on my keyboard. Can that really be true? This seems completely mad to me.

Considering updating my old package COSVAM, which treats complex-octonionic-valued scalars, vectors, and matrices, first of all I want a much better type check of whether an expression is indeed a complex-octonionic scalar. A complex-octonionic-valued scalar is a linear combination over the complex numbers of the eight units of the octonions 1,e1,...,e7, say. So all the following expressions are valid examples of complex-octonionic-valued scalars
expr1 := 10;
expr2 := e1;
expr3 := e1*I;
expr4 := e1*cos(t)+e2*sin(t);
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