Questions on correct (or improved) formulation of Mathematica code to achieve particular results. Use this tag (not "symbol") for questions about all those odd @@ /@ # & and ~ characters.

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5
votes
3answers
423 views

What is the right way to write a function that includes other functions?

I want to include multiple sub functions: $b(x) = 10x$ $w(x) = s + b(x)$ $c(x) = x^2$ into two main functions: $ua(x) = w(x)-c(x)$ $ub(x) = w(x)-c(x)^2$ As a reaction to this answer, I wrote ...
21
votes
1answer
525 views

Shorter syntax for Fold and FoldList?

I find it tedious to write out the following: a = {1, 2, 3, 4}; Fold[f, First @ a, Rest @ a] f[f[f[1, 2], 3], 4] It ...
0
votes
1answer
66 views

Combining functions - is this a case for Piecewise?

I have a function $Eb1$ which was the subject of a question I asked recently - you can see it here on stack exchange. Now, in that example it's specified between a boundary $r_n$ and $r_o$ where $r_o ...
2
votes
1answer
62 views

How to joint symbolic expressions together [duplicate]

I want to joint symbolic expressions together to create a another symbolic expressions. one way to do that is as follows: ...
2
votes
2answers
85 views

Using Table with arbitrary number of variables [duplicate]

Let $P=\{p_1,...p_n\}$. I would like a way to implent Table[Expression,{$p_1$,lim},{$p_2$,lim},...,{$p_n$,lim}] where n and lim are parameters defined by the user. Any ideas?
8
votes
1answer
178 views

Extract what symbol is set by SetDelayed, Set, TagSet, UpSet, SetAttributes, etc

One of the recent features of the Mathematica Plugin for IntelliJ IDEA (www.mathematicaplugin.halirutan.de) is a Structure View which let's you see information about several definitions that are done ...
4
votes
2answers
378 views

Scalar product operator of complex vectors

What is the scalar product operator for complex vectors (or matrices) in Mathematica? The usual $Dot[]$ doesn't work. E.g. here is what the Mathematica gives $$\{1,0\}.\{I,0\}=I$$ but the answer ...
0
votes
1answer
256 views

How to output a bat file and execute it?

I tried to write a bat file which helped me rename files. Command to do this in that file is "ren file1 file2" which is equivalent to RenameFile[file1,file2]. ...
5
votes
2answers
199 views

Syntax highlighting conflict

I'm trying to syntax highlight this expression: x=$\sqrt{\pi }$//N and from various sources I've learned that x (the assigned symbol) belongs to context Global while the Pi and N belongs to System. So ...
0
votes
0answers
79 views

My “N” turned red randomly [duplicate]

For some reason my N function showed up in red even though I haven't noticed it in that color before. The color actually makes the code much more readable but I just don't know if I should be alarmed ...
0
votes
1answer
190 views

Getting “Null” output from package?

I have a script written to test a package as follows: ...
1
vote
1answer
50 views

Correctly substituting a matrix into a scalar equation [duplicate]

I am having trouble correctly substituting a matrix into an (originally) scalar equation. For example: A = {{3, 1}, {1, 2}} cp = CharacteristicPolynomial[A, x] ...
4
votes
1answer
101 views

Highlight the same symbol throughout notebook

Once I saw people using Matlab use a keystroke shortcut that made all the same symbols as a selected symbol become blue. I am wondering is there is a function in Mathematica that is similar. If so, ...
8
votes
1answer
111 views

Does the syntax coloring I see indicate a real problem?

I need a behaviour provided by: x = 2; Block[{x = HoldForm[x]}, x] x FrontEnd marks ...
0
votes
2answers
74 views

Setting an element of an array to a value

This may be a simple syntax question, but for some reason I've been having trouble with it. Suppose we have an array arr, and we want to set one of the elements to ...
1
vote
1answer
92 views

Sort lists of vertices {indegrees, outdegrees} by indegree

in = VertexInDegree[F]; out = VertexOutDegree[F]; I want both in and out to be ordered by in. Example: graph has nodes a,b,c with indegrees 1,2,0 and outdegrees ...
2
votes
0answers
51 views

Why is `Cell` > `Convert To` > `InputForm` not invertible?

I sometimes post code to PhysicsSE, and I usually convert it to InputForm first before posting, in order to avoid pages and pages of ...
0
votes
3answers
85 views

Half kth term if n is even and k=n/2?

I am trying to write a function which will perform the equation in the attached image. So far, I have: ...
6
votes
0answers
331 views

Do any mainstream text editors support Wolfram Language syntax for highlighting?

Syntax Highlighting for Mathematica on a Blog There is the above, but I'm not terribly excited to install rogue packages. For example on github, I share lots of Mathematica code. I see no way to ...
0
votes
0answers
118 views

Meaning of backtick in conjunction with units [duplicate]

In this fragment from an equation solution the backtick is used twice: ...
0
votes
1answer
247 views

How to plot a region bounded by three equations?

I'm very new to this website. I am having trouble plotting a 3 dimensional region bounded by these equations: ...
4
votes
2answers
153 views

Replacing a function in defined expressions

I'm having a little trouble with substituting functions into an expression. A minimal example is as follows: ...
0
votes
0answers
64 views

TableDirection in TableForm

I got confused about what does "the outermost dimension" and "the first dimension" mean in the document I snipped. Does it mean row or column?
4
votes
2answers
252 views

How can I avoid getting the error message Goto::nolabel in my code?

If anyone could suggest a reason why Label[begin] ... Goto[begin] would return Hold[Goto[Begin]], and (better) how can I avoid ...
1
vote
1answer
52 views

How to set the values into some variables from different lists [duplicate]

I have a list of Values and a list of variables. I want to set the Values into Variables. Assume the following code: ...
1
vote
1answer
305 views

Compile with array operations

When I use the function f with only the Module ...
0
votes
1answer
81 views

Determining whether or not an expression is an integer

I'd like to define a function that controls if a certain number is an integer, rational, algebraic and so far. First, I tried generating a list of those numbers: ...
6
votes
1answer
112 views

A question about two ways to use Default

Usually we define a function with default values by the syntax x_:default, but there is another technique to do this by registering a global default value with ...
1
vote
2answers
152 views

MapThread with List Manupulation

I have the following three lists: ...
1
vote
1answer
101 views

How to input pure function to package?

I would like to input a pure function into a custom written package, but am running into a variety of errors. The package I have created is as follows: ...
1
vote
2answers
748 views

How to evaluate Modules in a notebook from another notebook?

I would like to create a notebook populated with several modules and be able to evaluate these modules by running a separate notebook. I have attempted several uses of the ...
0
votes
1answer
129 views

Normalize equation in NDSolve?

I have numerically solved and plotted the solution to the Mathieu equation using NDSolve successfully, as below: ...
6
votes
4answers
187 views

How to select only NotebookObjects that are referring to ordinary notebooks? (not palettes etc.)

There is of course function Notebooks[] But, unfortunatelly it hasn't got useful options in this context. My question is how to pick ...
2
votes
1answer
93 views

Why there is no SlotSequence (##) form analogical to #[[ ;; n]]

I'm aware that this may be closed as offtopic but there are people around with "offtopic" knowledge :) So, in List context we can: ...
0
votes
1answer
198 views

Issue with Compile

The following code works fine with the the function f defined as a module, however, when I convert it to be a compiled function, it gives me errors. Can some one ...
11
votes
3answers
213 views

Head of a MatrixForm expression?

An example in http://www-zeuthen.desy.de/theory/capp2005/Course/hahn/mathematica.pdf amounts to the following ...
0
votes
1answer
65 views

Convert variable into function

Sorry if this is a duplicate, but I have a variable called H. H is some complicated function of ...
2
votes
1answer
102 views

MapThread over a nested list

This may be a simple question. Please close it if it is already answered. I have a nested list kr = {{35, 32, 27, 20}, {36, 33, 28, 21}, {37, 34, 29, 22}} I ...
0
votes
1answer
68 views

Square root of a value defined in a finite field?

I am trying to find the right way to compute the square root of a number defined in a finite field. For example, ...
1
vote
4answers
389 views

Finding a number which has the same remainder when dividing certain other numbers

I am having some trouble with formulating my problem in Mathematica for this question: Is there a number greater than 1 which leaves the same remainder when it divides into 1716, 2154, and 4271? ...
0
votes
0answers
44 views

Using Table[ ] vs using Do[Append [ ] ] [duplicate]

Is it generally better/faster to use the Table function over using Do[Append []]? For example, I have this piece of code: ...
4
votes
2answers
221 views

How to define the irrational domain or any other arbitrary domain?

I have found no way to define the domain of Irrational numbers. I can easily define a test to see if a number is irrational by defining: ...
0
votes
1answer
79 views

How to write series of Do[ ]'s with a single Table[ ]?

Edited to provide more information (sorry I don't know how to format matrices here) I would like to replace: m = 4; ...
1
vote
0answers
160 views

Why is my answer being displayed with “Subscript^(0,1)[a,b]”?

I type in my equations using ctrl+- to make it look nice and my answer outputs in "Subscript^(0,1)[a,b]" form? What is going on? In the answer some bits are displayed with the actual subscripts and ...
3
votes
1answer
127 views

Differentiating a Dot Product

I apologize if this type of question has been asked before, but a preliminary search turned up nothing. I would like to differentiate dot products. For example, consider taking a derivative with ...
0
votes
2answers
135 views

How to display output as symbols?

I have this piece of code which populates a matrix following different rules depending on row and column number: ...
3
votes
1answer
108 views

Why is ^^ff not the same as ^^ToExpression[“ff”]?

I want to convert a hexadecimal string to a decimal (base 10) number: 16^^ff 16^^ToExpression["ff"] The 1st line returns the correct answer of 255, while the 2nd ...
0
votes
1answer
139 views

Holding Input Windows

I am creating a Mathematica document which contains a list of proofs in various fields of Mathematics so that I can easily review whenever I would like. First, I create a large set I call 'proofs' ...
2
votes
2answers
111 views

Return only one numeric solution to equation [duplicate]

Consider a simple plane equation 2x-3y+4z==7 I just want some position vector on that plane. For example, {7/2,0,0} would be ...
1
vote
1answer
263 views

Looping with NDSolve?

I have a series of PDE equations that are solved with NDSolve for certain variables $a$ and $b$ - Now, I want to see the output at a time $t$ as $a$ and $b$ change; so I was thinking of a loop ...