# Tagged Questions

Questions on attributes of functions.

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### {Protected, ReadProtected} System symbols give “Set::write: ”Tag * in *[v_] is Protected" on first try

Run Quit, then Unprotect@AbelianGroup; AbelianGroup[v_] = 0; Protect@AbelianGroup; where instead of ...
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### How do I restore HoldAll, HoldFirst, HoldRest attributes of Inactivated functions

Let f be defined as follows: ClearAll[f]; SetAttributes[f, HoldFirst]; f[1+1] (* f[1+1] *) The ...
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### What Heads do not have the attribute NumericFunction, but still give True in NumericQ?

The following expressions give True in the NumericQ test: ...
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### Argument attributes for pure functions [duplicate]

In his book, Leonid Shifrin says: One important limitation of the # - & notation for the pure functions is that it is ...
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### Pure function with attributes of arbitrary number of arguments: Is it possible?

Mathematica allows to define pure function, like Function[{a, b},Length[Unevaluated@a]{b}][1+2,2+3] (* ==> {0} *) Pure functions in Mathematica can take an ...
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### Defining a symbolic inner product

So I have some rules for a symbolic inner product that work for quite a lot of cases: ...
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### How is Attributes protected and yet can still be set?

The Attributes function itself has the attributes: Attributes[Attributes] ...
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### Map vs listable [duplicate]

What's the difference between setting a function's attribute as Listable and using Map? I understand that ...
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### Pattern does not match with Orderless head

Why does the following pattern matching not succeed? ...
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### MatchQ failing in some cases with Hold [duplicate]

Could someone clarify why the first of these MatchQ finds a match whereas the second does not? (I'm using version 10.0, in case that matters.) ...
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### Where are examples of packages that are locked?

I wanted to see some packaged whose core functions are locked, but I couldn't find any. Is anyone protecting their code with the Locked and ...
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### How to get f[x] to match with f[c_., x] when OneIdentity doesn't match

After setting: SetAttributes[f, OneIdentity] Default[f] = 1; We have the following successful matches: ...
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### how to differentiate formally?

I have been wrapping my head around this for a while now and I have not found a solution so far. I want to work with an arbitrary number of variables in mathematica and use some built in functions. ...
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### Manipulate curves [duplicate]

I want to draw curves with manipulation. When I use the following code, I receive nothing. ...
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### How to define a function that is Listable for some but not all arguments?

I want to define a function f[x,y] that is Listable for only the first argument, not the second. If we use ...
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### Attributes with Pattern test

Probably this question has no application but it helps understand basic issues about Attributes and functions. I was writing a piece of code where I accidently ...
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### Orderless and Sequence

I just ran into the following subtlety. Let us consider a function f with attribute Orderless. ...
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### Why there is only HoldFirst but no HoldSecond, HoldThird, …HoldN?

I feel that this must be a duplicate. But I just can't find such a post. Mathematica has HoldFirst, HoldRest, ...
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### Follow-up to “How to differentiate formally?”: Efficiency concern

In link to "how to differentiate formally?" and particularly to the answer by @Jens, I want to do something like this: ...
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### How do Dynamic Attributes work?

Reading in the doc, it is mentioned in the example of Dynamic that this way of writing the code does not work: ...
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### Built in function without Attributes Listable works as if it has Attributes Listable

Can Built-in function works as if it has Attributes Listable even if it doesn't have that ...
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### Given the OneIdentity attribute why is GCD[a] evaluated to GCD[a]?

GCD has attribute OneIdentity so I expected GCD[a] being evaluated to a?
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### Documentation on the attribute OneIdentity [duplicate]

The documentation on the attribute OneIdentity says OneIdentity is an attribute that can be assigned to a symbol f to ...
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### How do you set attributes on SubValues?

SubValues, as discussed in a previous question, are declared as follows ...
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### make trace of a matrix listable?

I have a list of 2 by 2 matrices and I want the list of their traces. I have been using Map[Tr,mylistofmatrices] But I wonder if there is a way to make ...
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### Orderless pattern matching

The MMA docs state that "In matching patterns with Orderless functions, all possible orders of arguments are tried". Why then does the following not work? ...
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### Package automated way of ReadProtecting all symbols

My template for building packages has, at the end, the following expression that automatically ReadProtects all symbols defined in my ...
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### How do I display function application with square brackets in traditional form?

If I type C[x, y] // TraditionalForm I get something that looks like C[x, y] But if I type ...
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### DiracDelta attributes

Is there any reason why DiracDelta isn't a NumericFunction but DiracComb is? I just ate a ...
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### Listable on first level [duplicate]

I have some function which take List as input. f[l_List]:=someActions[l] I need apply this function to a list of lists. Now I ...
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### How to understand the difference between Sqrt and Log after ClearAll them

I came across this post, here I change the last line of the code Unprotect[Sqrt]; Sqrt[x_] = "blahblah"; Protect[Sqrt]; Sqrt[2] "blahblah" ...
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### How Unevaluated works Through its Attributes?

Check this example: ...
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### Slowdown of Flat attributed function

I was trying to write an associative function f using the attribute Flat. ...
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### Numeric-type attributes for symbols (analog of NumericFunction)

Is there an attribute for symbols that makes NumericQ give True? For example Pi and ...
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### Listable functions thread over Associations; is this documented?

Thanks to a somewhat misapplied use of MapThread I learned of this behavior: ...
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### How to restore function attributes to default

Adding an attribute to a function is easy and clearing attribute is easy also. But I don't know really how to restore the attributes of a function to its defaults. All I do is quit the kernel or close ...
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### Strange Behavior when making Equal Listable in Pick

While trying to make this problem more efficient I tried different methods and dabbled with making Greater and Equal ...
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### Plotting attributes of vertices in WattsStrogatzGraphDistribution[n, p, k]

I have a graph WS = RandomGraph[WattsStrogatzGraphDistribution[n, p, k]]. I need to plot several characteristics of each v: the ...
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### Why is either Listable or HoldFirst not working?

Starting with a fresh kernel, I evaluate the following: ...
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### Custom attributes?

Is it possible to assign custom attributes to symbols and check them later? SetAttributes[a, b] says ...
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### How to protect functions in a Mathematica Package?

I'm writing a Mathematica Package with many functions, but only two can be seen/public. I have: ...
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### Mathematica: How to create a function that returns a property similar to how LinearModelFit works?

I'm trying to write a custom function in Mathematica, myFunc[x]. I want to be able to define properties of the function so that the user can call ...
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### How can one write a robust ListableQ function?

I would like to have a test that determines if a particular function is Listable. In the case of Symbols this is merely a matter of checking Attributes. ...
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### Apply N only outside a certain function

1 + f[1] // N gives 1. + f[1.] I don't want the argument of f evaluated by N; I ...
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### The Flat Attribute, Unevaluated and the Evaluation Process

To make this question easy to follow let's give some symbols a couple attributes. Attributes[f] = {Flat}; Attributes[s] = {Orderless}; Now consider the following:...
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### Map and Scan ignore HoldFirst

I am trying to write a simple function that takes a list of data and outputs it to a file. I'd like the name of the file to be the same as the variable that holds the list. It seems that giving a ...
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### Why is NHoldFirst not propagated to symbolic derivatives?

I encountered a nasty problem that N cannot evaluate expressions containing a symbolic Derivative of a multi-parameter function ...