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Questions tagged [built-in-symbols]

Questions related to handling built-in symbols and functions, for example why they behave a certain (possibly unexpected) way.

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31
votes
2answers
1k views

List of atomic expressions

I was surprised to see Graph objects are atomic. Is there a way (through documentation or programmatically) to find all atomic heads? The ones I know of are: <...
10
votes
1answer
324 views

Defining my own invisible operator

There are some invisible operators in Mathematica (\[ImplicitPlus],\[InvisibleTimes],...
1
vote
0answers
97 views

Define an operator without Built-in Meanings containing a Power function [duplicate]

I would like to define the following operator: $$ \left[T^{(j_{1})}\otimes U^{(j_{2})}\right]_{m}^{(j)}=\sum_{m_{1},m_{2}}\left\langle j_{1},m_{1};j_{2},m_{2}\big|j,m\right\rangle T_{m_{1}}^{j_{1}}U_{...
11
votes
4answers
520 views

When should I use Apply (or Function) and when @@ (or &)?

This is a rather general question, which I fail to answer myself. I guess it is mainly due to my insufficient knowledge of the precise terms. If I understand correctly, the following are equivalent: ...
2
votes
2answers
348 views

How to unprotect GeneratingFunction

I'm trying to add custom downvalues for GeneratingFunction, and to do so I thought I just had to Unprotect it. However, that ...
8
votes
1answer
258 views

Builder pattern for complex objects construction

Intro I was watching "UnRisk-Q Instrument Builder" talk (https://www.youtube.com/watch?v=Xx3goIBpOdE) and those guys use builder pattern to build complex objects like this: ...
20
votes
1answer
349 views

Why are some option values symbols, other strings?

Is there a rationale, beyond historical accident, why some Mathematica option values are strings, while others are symbols? It seems natural that some value spaces, e.g. named color schemes, are so ...
24
votes
4answers
2k views

ReadList problem related to Record type

A simple file reading issue is baffling me here. I am reading a around 200 MB textual file in .dat format. Now the file contains many lines but to phrase my problem ...
6
votes
1answer
779 views

Using the symbol I for electrical current [duplicate]

I would like to use the I as a symbol for the electrical current. How can I redefine it, so it is not interpreted as the imaginary unity?
8
votes
2answers
589 views

Replacing product expressions - named vs. unnamed pattern?

Suppose I have an expression of the form a b c d + x y z The FullForm of this is ...