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25
votes
2answers
597 views

Copying one symbol into another

I would like to know how can I completely copy one Symbol to another. When I say copy, a refer to UpValues, DownValues, ...
23
votes
3answers
1k views

Emulating R data frame getters with UpValues

What's the best way to emulate R's data frames functionality? This includes the ability to select rows and columns in a 2-dimensional table by the string identifiers positioned typically in the first ...
26
votes
4answers
2k views

Do people actually use UpValues?

I know what they are and how to define them. They have to serve some purpose - else why include them? But I never used them and all examples on this site and the docs never show a practical use of ...
11
votes
3answers
413 views

How can I hold UpValues but evaluate other expressions?

Consider these definitions: own = "OwnValue"; down[_] = "DownValue"; sub[_][_] = "SubValue"; N[n] = 3.14; _[___, up, ___] ^= "UpValue"; The attribute ...
6
votes
2answers
239 views

How to customize derivative behavior via upvalues?

I'm having trouble getting customized derivatives (defined using upvalues) to behave in sane ways. By this I mean that I'd like to define a derivative using an upvalue and then have Mathematica apply ...
9
votes
2answers
348 views

Using up-values and down-values

I have a problem I'm trying hard to find a solution for, although I don't know if a solution exists. The following rules produce the result e[2].f[] ...
17
votes
1answer
522 views

Upvalues, TagSet and UpSet, what's the difference, when should a use each?

Some of the big mysteries of Universe Mathematica for me is the application of UpValues. I know about this question and know the very poor Mathematica documentation on that. I'm very curious to know ...
4
votes
1answer
199 views

Inheritance in Mathematica using pattern matching on UpValues

Edit: I think in my original post, I missed emphasizing the main point. This is mainly a pattern matching question. If you're interested in the 'why' of this question, please read the original post ...
4
votes
1answer
203 views

Access curated or locally stored data with curated data functions?

Say I have a toy package, something like: ...
7
votes
1answer
101 views

How to assign up-values for `Derivative`?

I have defined several custom analytic functions. Here is the simplest example: ln[x_, a_?NumericQ] := Piecewise[{{Log[x], Re[a] > 0}, {-Log[1/x], True}}] ...
18
votes
2answers
355 views

What does f_[whoCalled]^:=f really mean?

I came across the following post by John Doty in this Google Groups discussion: On Friday, January 11, 2013 8:23:16 PM UTC-7, amzoti wrote: It is clear the Mathematica uses Lisp as one ...
10
votes
4answers
572 views

How to use pattern matching to assign values to Subscript[f,x_]?

I want to define two subscripted functions Subscript[f,1] and Subscript[f,2]. To keep the assignments local, I would like to ...
9
votes
2answers
204 views

How to define UpValues in a different context from within a package

I'm trying to create a function (in a package) to import a lot of data and create a symbol with UpValues to return specific results about the data. I've got it working fine in a regular notebook, but ...
6
votes
1answer
165 views

Problem overloading D[] using UpValues

First I define an entry of UpValues overloading D[] for expressions with head ftest: ...
4
votes
2answers
384 views

Overloading conjugate operator for a particular function

I trying to modify the behaviour of the built-in Conjugate[] operator on a particular function I have defined, to take into account that some of its variables are ...
3
votes
3answers
139 views

UpValues evaluation with Dot operator

I would like to simplify some database notation, and I'm doing some tests with UpValues for that. For example, if I set this Upvalue fot tab1: ...
2
votes
1answer
106 views

Experiment with TagSetDelayed involving Part

Reading Associating Definitions With Different Symbols, I was intrigued by this: You can think of upvalues as a way to implement certain aspects of object-oriented programming. A symbol like ...