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

1
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2answers
49 views

CountryData and RailwayGaugeLengths

Looking to see how to extract out just the length for this search: ...
1
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1answer
29 views

From algebraic symbols to symbolic functions

i have a code which gives an output of this kind: rrr=2*f+1; Now i define a simple function: f[x_]:=3*x+2; How should i do ...
0
votes
0answers
25 views

Mathematica does not recognize NestGraph

When I try to use the built-in command NestGraph, Mathematica doesn't recognize it. So it just outputs whatever I put in without doing anything. Do I need a special package for NestGraph?
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votes
0answers
36 views

How can I simplify expressions correctly?

the final output of my code gives this expression which i call ttt: ...
1
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1answer
18 views

Substitution of expressions for the output

I have a code which gives this kind of output : W = Sum[v[j]*b[j], {j, 1, 3}]; AA = (v[1]*b[1] + v[2]*b[2] + v[3]*b[3])*2 + 3 ; I know that if i want to ...
3
votes
2answers
171 views

Transferring DownValues

I have a code in which I define something like this: cc[1, 2] = 1; cc[2, 6] = 12; cc[3, 7] = 3; After some manipulation I define a sort of temporary variable ...
1
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1answer
43 views

Setting to zero non defined array variables

I have a situation like this (for example): ...
4
votes
2answers
672 views

Replacing dot by *?

I am unable to replace dot by *. Replace[a.a, .-> *] Is there any solution to get this done?
4
votes
2answers
88 views

Power Function and Non Commutative Multiply

I'm trying to figure out the best way to define a Power function for non commutative multiply that retains some of the regular features of the ordinary power function. As of now, what I've been ...
3
votes
1answer
77 views

What does the $ sign do? [duplicate]

I saw this uses $, but it was not clear what does it do there. ...
6
votes
5answers
228 views

First evaluate in place all subexpressions matching pattern before substituting result

ReplaceAll[expr, {patt1:>rhs1, patt2:>rhs2, …}] works by looking for and making all possible replacements of subexpressions in ...
7
votes
3answers
515 views

Is there a built-in function to get the centroid of a table?

Suppose I have a table with some data that are 'lumped' around some central location, such as the dummy example ...
6
votes
2answers
125 views

How to create non-rectangular array with Array?

From the answers to this question, I learned that the recommended way to construct a symbolic sum of terms in an expression is to use Array. But I'm having a ...
1
vote
1answer
43 views

Low level built-in function to transpose expression (not array) [closed]

I have an expression like this F[G[1, b], G[3, y], G[4, y], G[5, u]] that I would like to Transpose to obtain ...
7
votes
2answers
117 views

Constructing expressions using Sum vs Array[… Plus] vs Plus@@Table[…]

For constructing a sum of terms which are symbolic, I noticed that in addition to ...
7
votes
2answers
210 views

How to obtain list of Installed Packages loadable by Get (<<)

When Get["MyPackage`"] is executed, Mathematica looks for a package in $UserBaseDirectory/Applications, and it does, it will ...
0
votes
0answers
26 views

Built-in function to know if a list is inside another? [duplicate]

For example, if the function is f[a_List,b_List] then in f[{a,b,c},{a,b}] and ...
0
votes
1answer
67 views

Is there an error pertaining to HypergeometricU function on functions.wolfram.com?

If one clicks on the last of the nine formulas on http://functions.wolfram.com/HypergeometricFunctions/Hypergeometric2F1/17/02/07/ one obtains Hypergeometric2F1[a, b, c, z] == HypergeometricU[a, b, a +...
1
vote
1answer
43 views

any possible meaning to a “terminal” slash (/)? [closed]

I've been directed to the web page http://functions.wolfram.com/07.31.16.0001.01 The first statement in the formula is ...
4
votes
0answers
53 views

Crossing a symbol like p, similar to HBAR

Is it possible in Mathematica to cross a symbol like p, similar to h-bar, used to denote the Planck constant? Picture in case of font problems: In case of h, we have HBAR, inputted as ESC-hb-ESC ...
2
votes
1answer
34 views

Question related to IntegerPart

I am having trouble understanding the following result: Through[{IntegerPart,FractionalPart}[{100 4.02}]] {{401}, {1.}} ...
6
votes
2answers
636 views

How to take top 10 built-in function

WolframLanguageSymbol has a property named Frequencies, such as ...
4
votes
1answer
77 views

Is there a PartDelete like there is a TakeDrop

TakeDrop is nice because after taking a subarray, it also returns the remaining subarray. But it is limited in that the part specification can only be ranges, and ...
2
votes
1answer
52 views

Get polynomial terms

Is there a command equivalent to that of Coefficient to get the terms of a polynomial which are a power of the variables? For example: func[(x^3 + x)^2] {x^2, ...
1
vote
1answer
70 views

Functions aren't executed

Can't figure out why Mathematica doesn't want to execute built-in functions? What can be wrong? Input: ...
-1
votes
1answer
61 views

meaning of variable equal dot [closed]

I came across a program which I have written in a simplified form. For[i=1,i<100, i=i+1; func = a x^i; func=. ]; What is purpose of "func=."?
4
votes
3answers
263 views

Faster trace of product of two matrices

I noticed that for the computation of the trace of a product of two matrices, using Tr[Dot[A,B]] is a little inefficient. Dot ...
9
votes
1answer
200 views

Table of precedence values for all System` symbols

Has anyone created a table listing the precedences for all symbols? Also, it would be nice if there were a function that for a given precedence value or interval, returned all the symbols with that ...
1
vote
0answers
39 views

Wigner-D in MMA

Can some nice MMA fellow explain to me why buit-in Wigner-D function is defined as $D_{mm'}^{J} = e^{i(\phi m+ \gamma m')} d_{mm'}^{j}(\theta)$ against the convention, used by most people on Earth, ...
0
votes
1answer
99 views

How to prevent simplification from Times to Power?

By default, Mathematica simplifies Times[f[x],f[x]] as Power[f[x],2]. In most cases it's fine, but I happen to have a code where ...
4
votes
1answer
57 views

What does $UseTextSearchQ do?

Mathematica 11.2 features a new built-in symbol in the Global` context: Global`$UseTextSearchQ What does it do, and how do I ...
8
votes
1answer
161 views

1 is not the SameQ as Null, but why might 1 be Equal to Null?

The command SameQ[1, Null] returns False which is what I would expect, but the command ...
1
vote
1answer
122 views

Implement edge contraction function which respects vertex weights

It seems that built-in EdgeContract function doesn't work properly with weighted graphs, to be more precise, I mean that if I'm going to contract edge $e$ which ...
3
votes
4answers
161 views

What is the inverse of the Position function?

What is the inverse of the Position? I have an array which contains the positions of elements and I want a function which returns an List which contains 1 where ...
2
votes
1answer
79 views

How does one plot an oblique/slanted cylinder within the plot range?

A Cylinder does not seem to have an option to make it oblique. A Tube has an oblique center but does not seem to have an option to make the end caps oblique. One could plot a cylinder or tube that ...
0
votes
1answer
53 views

Why the export the Graphics or Image to local file [closed]

I note the Put cannot export the Graphics or Image,I mean this code will be failure. ...
5
votes
4answers
238 views

Mean of a list of lists (vector) with missing values

I understand, from Calculating the mean of a list with NaN values, that one can preserve structured data with missing values, and still calculate a mean, using ...
7
votes
1answer
311 views

Geometry computations add-on for Mathematica?

I came across the problem of calculating the circumcenters of triangles symbolically within another algorithm (as well as possibly doing other similar geometry computations). I was hoping Mathematica ...
10
votes
2answers
356 views

Is it safe to Unprotect everything? What are the implications?

What is the reason for built-in symbols to be Protected? What happens if I Unprotect built-ins and add my own ...
1
vote
1answer
89 views

Having trouble defining a function with head Superscript

I wish to define a function in the following form, ...
5
votes
1answer
75 views

Unexpected result of Clip

A simple question. Here Clip works as documented: Clip[0.5, {0, 0}, {0,1}] (* 1 *) Values larger than 0 are replaced with ...
23
votes
2answers
1k views

List of symbols without built-in meaning

Is there a list of all symbols with special display forms but no built-in meaning? That is, operators that are described in the tutorial Operators without Built-in Meanings?
4
votes
1answer
81 views

Internal function overload when calling ReadString on a fresh kernel

Problem description: I am capturing all FE messages to redirect them to my own window while blocking them from showing in the evaluation notebook using this method by rcollyer. It works great, but I ...
31
votes
3answers
2k views

Why is Plus so much slower than Total?

Why is Plus so much slower than Total for summing lists? ...
5
votes
0answers
51 views

Why ReadList ignores NullRecords for Number?

When thinking on this recent question the immediately obvious solution which came to my mind was to use ReadList with options ...
1
vote
0answers
77 views

Changing operator precedence

Is there a way to change operator precedence for built-in symbols? I'd like \[TensorProduct] (which I redefine to ...
25
votes
4answers
949 views

What's purpose of the new function BinarySerialize?

11.1 introduced a new function BinarySerialize, but I don't know what it can do better than the traditional method.Its behavior is very similar to ...
1
vote
0answers
74 views

Controlling precision/accuracy inside built-in commands

Some functions (such as Erf) appear to use NIntegrate internally. In such cases, is there a way to control such options of ...
3
votes
2answers
219 views

NetModel's cache in which folder?

NetModel will produce a big cache file after you use it first time. ...
1
vote
0answers
47 views

How to run the command 'Distribute' on large product of multivariable polynomials without simplifying it

I am new to Mathematica, so pardon if question is trivial. I am trying to expand (i.e multiply out the factors) an polynomial expression $d$, with many factors, obtained as a result of taking ...