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22h
comment How to enter matrices in block matrix format?
This point about {t}\[Transpose] being necessary is important and subtle: Mathematica (to its credit) does NOT finesse the fact that vectors must be either 1 x n or n x 1 matrices, that is, explicitly either row or column vectors. Pretty much everything else (including my beloved Golub & VanLoan) does (tho G&VL have the grace at least to say they do). I find the conceptual hygiene forced by Mathematica to be refreshing and helpful.
23h
comment Operator-Input Form for Lists?
Interesting that the documentation goo.gl/IyQMeF states this method obscurely: "Note that you can use... to start building..." [emphasis mine] after presenting the keyboard shortcuts as commands that "add" to a matrix or table that must presumably already exist, the only clue being that it states that "this" is often more convenient than the menu, without explicitly stating that "this" is "bypassing the menu." I'm looking for an excuse why I could have missed this for so long, so I'll criticize the documentation.
23h
comment Operator-Input Form for Lists?
I wish I'd known this 25 years ago. I'm resisting my OCD telling me to go back-date the 25,000+ notebooks in my collection!
23h
accepted Operator-Input Form for Lists?
1d
asked Operator-Input Form for Lists?
1d
comment Backslash commands in strings?
It's relevant to the answer, but not as direct as the answer above. I'm upvoting because it's helpful and useful.
1d
accepted Backslash commands in strings?
1d
asked Backslash commands in strings?
Jul
24
awarded  Nice Question
Jul
22
comment MatchQ-ing Associations (MMA 10)
@alancalvitti -- yes, it can, but, so far as I know, there is no standard for this in JSON and developers often write really bad code for testing equality of JSON objects. Mathematica has a standard (if obscure) order for terms in expressions and freely reorders things for you in evaluation. But an Association is probably reordered in Hash order or Trie order or something else altogether and would have to be reordered for pattern matching. That's my guess -- just a guess -- why Taliesen said it's difficult to be efficient.
Jul
22
comment MatchQ-ing Associations (MMA 10)
A possibly similar problem arises, for instance, in deciding whether the two JSON objects {a: 1, b: 2} and {b: 2, a: 1} are equal; the problem explodes with size, requiring either some arbitrary sort on the keys or considering $n!$ possibilities (modulo nesting).
Jul
22
comment MatchQ-ing Associations (MMA 10)
I can see that pattern-matching over the contents of an Association would be difficult. Thanks for the info!
Jul
22
accepted MatchQ-ing Associations (MMA 10)
Jul
22
asked MatchQ-ing Associations (MMA 10)
Jul
21
comment Struct equivalent in Mathematica?
@Leonid -- I have done some at-scale, production-level systems in Clojure and highly recommend it :)
Jul
21
awarded  Revival
Jul
20
comment Struct equivalent in Mathematica?
The careful handling of mutability, structure-sharing, and software transactional memory in Clojure might be the most sophisticated available in the world today (goo.gl/dG3g3). If I were to go whole-hog in Mathematica with a data-structure library, I would learn from Clojure.
Jul
20
answered Return struct from function (with DownValues)
Jul
19
awarded  Inquisitive
Jul
18
comment Opacity limitations?
@celtschk -- yes, the second is what I wanted. Looks like this is a MMA 10 issue (or at least a non-MMA 8.0.0 issue :) and I'll file a bug.