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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0
votes
1answer
72 views

While Loop Not Looping [closed]

no matter what I do, the following function always returns the first v. This does does not make sense to me at all. It should loop and reevaluate v and only stop when v matches the condition. What am ...
0
votes
1answer
103 views

Position of elements in a list satisfying some criteria - Understanding the syntax [closed]

From this post: if one wants to know the position of the elements of a list that satisfy some criteria, (s)he can do something like that: ...
1
vote
2answers
60 views

How to get the outermost command evaluated first?

I have an expression like ToString[Stuff[...]]. I plan on having the Stuff[...] be manipulated as a string according to the output of other parts of the program. The problem is that Mathematica tries ...
2
votes
1answer
139 views

Array in Sum in Minimize - error “Part specification x[1] is neither a machine-sized integer”

Help please M = 10; z = Array[x, M] {x[1], x[2], x[3], x[4], x[5], x[6], x[7], x[8], x[9], x[10]} ...
2
votes
1answer
76 views

RegionUnion issues with many Regions

The new RegionUnion[] function is just what I needed if only I could get it to work. I have many non-overlapping regions that I will need to use as plotting domains ...
3
votes
3answers
1k views

Superscript prime symbol

x\[Prime] looks like $x_'$, ugly right? Is there a way to make a symbol with prime to look like $x'$? That's what I'm trying right now: ...
26
votes
6answers
612 views

Constructing symbol definitions for With

I would like to be able to define two arrays, one containing symbol names and one containing the values of those symbols, for use in constructs such as With. For ...
0
votes
0answers
42 views

How can I mix // with a function of two arguments? [duplicate]

I often find myself using // when playing around with expressions, but it is always cumbersome to have to switch to the full notation just to apply a function of ...
11
votes
5answers
767 views

Postfix Double Slash Notation with Multiple Parameters [duplicate]

Examples A convenient shorthand that I use frequently is the "double slash" notation to string commands together. For example, I can write: ...
1
vote
1answer
102 views

How a novice user better understand the Q/A [duplicate]

A novice user reading Q/A here: I sometime need to just understand the syntax and meaning of commands exampled here. where is the best place to find it?
70
votes
2answers
3k views

Flatten command: matrix as second argument

One thing I could never wrap my head around is how Flatten works when provided with a matrix as the second argument, and the Mathematica help isn't particularly ...
2
votes
2answers
914 views

Several functions in one RegionPlot with different grayscale

I try to plot the following, but something seems to be wrong in my code and I can't figure out how to fix it: ...
1
vote
0answers
93 views

SyntaxForm not correctly parsed by FrontEnd

When using TagBox with SyntaxForm, I noticed sometimes it is not well parsed by the ...
1
vote
1answer
76 views

Appending functions to a list [duplicate]

Could someone please explain the difference between these methods, and possibly a nicer way to get the first result? (This is a toy example and in my real program I'd like to use ...
4
votes
1answer
235 views

How to see abstract syntax tree of Wolfram Language expression

I mean, suppose I have this expression: 2 + 2 I want to get something like this: Plus[2, 2] as an output. I've tried FullForm, but this just evaluates 2+2 and returns 4. Is this even possible?
7
votes
3answers
4k views

Matrix Multiplication in context of row and column vectors

I've been looking at some matrices in Mathematica and I've noticed something very weird: They're extremely temperamental when it comes to dot products! For example, if I have the following, ...
5
votes
4answers
281 views

Defining a function with parameters as variables

I have an expression V = (a[1] + a[2])b[1]. How would I define a function of a[1], a[2] and ...
3
votes
3answers
178 views

Is it possible to use infix notation ~ for functions with one argument or more than 2 arguments?

According to a Mathematica textbook, we can write N[x,n] by using infix notation as x ~ N ~ n. How about other functions with ...
13
votes
2answers
552 views

How to embed an image into a string?

Note: The bug described in the post is in Mathematica 9, and has been fixed in 10.0. The documentation for String contains the following statements: Strings ...
4
votes
2answers
75 views

Why can't I pass in a product of matrices in my modified matrixform? [duplicate]

In attempt to build a function that would work like MatrixForm but would wrap a matrix with brackets, I tried the following function: ...
1
vote
1answer
125 views

How would one minimize with respect to an unknown number of variables?

Say I had a function like the following: f[n_] := Sum[a + Subscript[b, k], {k, 0, n}] Such that ...
5
votes
3answers
434 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 ...
0
votes
1answer
75 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
68 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: ...
5
votes
2answers
545 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
326 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]. ...
0
votes
1answer
225 views

Getting “Null” output from package?

I have a script written to test a package as follows: ...
5
votes
2answers
213 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
88 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 ...
1
vote
1answer
52 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
115 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
113 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
82 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
101 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 ...
3
votes
0answers
59 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
91 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: ...
3
votes
2answers
2k views

How does one specify Neumann conditions for NDSolve?

I have a series of functions defined in my notebook, and then want to use this to solve a diffusion-reaction type equation. At the moment, something like this works: ...
7
votes
0answers
434 views

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

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
137 views

Meaning of backtick in conjunction with units [duplicate]

In this fragment from an equation solution the backtick is used twice: ...
28
votes
2answers
1k views

Meaning of backtick in floating-point literal

If I compute, say, 1/3//N, Mathematica displays 0.333333 as the result. When I copy that output to use elsewhere, the paste ...
0
votes
1answer
346 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: ...
7
votes
4answers
194 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 ...
4
votes
2answers
164 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: ...
4
votes
2answers
311 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 ...
0
votes
1answer
221 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 ...
1
vote
1answer
344 views

Compile with array operations

When I use the function f with only the Module ...
0
votes
1answer
91 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
113 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
158 views

MapThread with List Manupulation

I have the following three lists: ...