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mat2list command - Thomas Ritschel - 02-17-2014 09:11 PM
I'm trying to convert a one-dimensional matrix (a vector) to a list.
The cataloque menu provides a function called "mat2list" which concatenates the rows of a matrix to just a single row. However, this is still a matrix object with square brackets, e.g. of type "4", which is not what I want (curly braces, type "6").
In contrast the oposite function "list2mat" works as expected.
Is there some other function for this purpose, or maybe some "type conversion"?
Thanks,
Thomas
RE: mat2list command - massimo - 02-18-2014 12:37 AM
Assign it to a "L" variable:
L3:=mat2list([[1,2],[3,4]])
Not very elegant, indeed.
Why not use some recursion in a CAS function?
lc(a):=PIECEWISE((length(a)) = 0,{},(length(a))>0,concat({head(a)},lc(tail(a))))
lc([a b c]) returns {a b c}
I like functional languages! BTW this is a classic example of tail recursion. Many functional languages translate it to a loop. It will be nice to know which is the CAS behavior.
RE: mat2list command - parisse - 02-18-2014 08:01 AM
Try convert(vector,23)
23 is the subtype of HP lists (Xcas does not make a difference between vectors and lists), 0 is for normal lists, 1 for sequences, 2 for sets.
And the CAS does not try to convert your code to a loop. It is interpreted like it was entered.
RE: mat2list command - Thomas Ritschel - 02-18-2014 06:57 PM
(02-18-2014 08:01 AM)parisse Wrote: Try convert(vector,23)
23 is the subtype of HP lists (Xcas does not make a difference between vectors and lists), 0 is for normal lists, 1 for sequences, 2 for sets.
That's what I was looking for! Thanks!
It's just a bit confusing that CONVERT in Home view means Unit conversion. So one has to use CAS.convert instead...
RE: mat2list command - parisse - 02-19-2014 07:38 AM
I'm modifying mat2list to return a HP list.
The same CAS convert command performs list subtype conversion, unit conversion and also some rewriting commands (and in that case you can use STO> as a shortcut, like 1_m Sto> _cm or x^4-1 Sto> * )