On 11/05/13 21:01, Waldek Hebisch wrote:
> Logically two dimensional arrays and matrices are the same thing
> Opinions?

I seem to remember using 'TwoDimensionalArray String' in '.input' scripts 
to hold and output tabular results. 'List List String' is not output as a 
table and 'Matrix String' is not valid.

At one stage I was considering writing a 'table' domain specially for 
outputting tabular results. The idea was to allow nice formatting of 
tabular output so, for instance, rows and columns would have text headings. 
Individual cells could be highlighted in various ways and so on. In the end 
I came to the conclusion that this would not work very well with the 
command line interface, a better solution would be for FriCAS to have high 
level interface to a spreadsheet front end.

On 11/05/13 22:49, Ralf Hemmecke wrote:
> What I rather question is that Matrix and Vector have no size in the
> type, so Vector(K) does not represent a vector space, but rather it
> represents the union over all n-dimensional vector spaces for all n.
> Same for matrix. *This* is what bothers me.

Yes, this always seemed like an anomaly to me, I assumed that was due to my 
lack of knowledge about FriCAS. I thought it should be a general principle 
that, the type system should be given the maximum opportunity to find 
errors (such as when attempting to add a 2D vector to a 3D vector) at 
compile time rather than at runtime. I thought this was one of the main 
benefits of having dependant types? I agree that there are times when 
multiple dimension vectors are needed, but these should be of a different 
type, in the same way that we have both Lists and Arrays.

Martin

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