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.

learn more… | top users | synonyms

3
votes
0answers
38 views

Java anonymous functions from JLink?

JLink is really great to act on Java objects and access Java static methods. I'm asking myself if there would be a way to have access to a more recent Java syntax that allows anonymous functions, ...
5
votes
5answers
217 views

Nested function with an increasing argument

If, for example, I have a nesting function like Nest[1 + x^n (#) &, 1, 3] it gives the result ...
0
votes
1answer
51 views

Compile decreases the number of returned list elements

I have: LogisticMap = Compile[{μ}, ({μ, #} &) /@ Union[Drop[NestList[μ # (1 - #) &, .2, 300], 100]]]; Then: ...
3
votes
1answer
108 views

Binary decision diagrams (BDD) syntax error

I am new here (and to Mathematica) and would like to rebuild a simple binary decision diagram that I found here https://en.wikipedia.org/wiki/Binary_decision_diagram A code has been provided as part ...
7
votes
3answers
82 views

TagSetDelayed on a function with a delayed value

I'm trying to automatically optimize cases when the user evaluates Length[returnsList[x_]] to instead use returnsLength: ...
4
votes
1answer
186 views

Why assign variables to empty curly brackets?

I am trying to read code and I see empty curly brackets. For example: abc = {} or ...
6
votes
2answers
145 views

Ignore some values at return

Is there Mathematica analogue of Python _ (underscore) or Matlab ~, a special variable, that can be used when a function returns ...
6
votes
3answers
316 views

How can I create currying functions using pure function syntax?

For example how can I write In: pureFunctionSyntax[myF] /@ {7, 3} Out: {myF[7, Log[7]], myF[3, Log[3]]}
6
votes
2answers
518 views

What does (0 &) mean in an evaluation? [closed]

My Mathematica code is this: Simplify[D[Sqrt[1 + (u')^2 + (-60 x - 20 u u')^2], u]] It returns this: ...
5
votes
3answers
605 views

Can symbols like + or * be used to denote the Plus and Times functions?

Can one do something similar to +[1, 2]? The point is that with one symbol you would be able to write expressions like ...
0
votes
2answers
65 views

Function input syntax [closed]

My functions are ...
1
vote
0answers
72 views

Meaning of Abs´? [closed]

A friend showed me the code below. r[i_] := {x[i, t], y[i, t], z[i, t]}; rji = r[i] - r[j]; solap = 2 a - Norm[rji]; FullSimplify[D[solap, t]] I'm unsure about ...
1
vote
1answer
34 views

Scan appears to work setting graph properties, but get error on property-read

This is a self-contained version of something a bit bigger - going for brevity. It is a bit synthetic, but there are applications I have in mind where the {{1,2}} will be replaced with real data, more ...
1
vote
2answers
71 views

Intersection of all sublists of a list [duplicate]

I want to get the intersection of all sublists of list in an easy way. ...
11
votes
1answer
158 views

The equivalent of dplyr mutate with Dataset

In R, there is a package "dplyr" that works on data.frame objects, which is one of the origins of the Mathematica Dataset construct. One of the things dplyr can do is "mutate" the columns of a ...
1
vote
1answer
80 views

Can I map a function over a sequence of arguments without making the arguments into a list first?

I would like to set evenFunction[f_][a_, b_, c_, ...] = f[Abs[a], Abs[b], Abs[c], ...] I have come up with two ways to do this so far. Use pure functions ...
5
votes
2answers
286 views

f /@ # & /@ # & /@ # & /@ # & /@ # & /@ # & /@ # & /@ matrix

How can one write f /@ # & /@ # & /@ # & /@ # & /@ # & /@ # & /@ # & /@ matrix in one line with arbitrary level and without using ...
0
votes
0answers
44 views

Solving Integral -syntax or interpretation problems

WA interpreter achievement not well this entry from Mathematica, steps need to see the full resolution input WA ...
0
votes
1answer
126 views

Convert code from C++ to Mathematica [closed]

I need to know how to convert the following code in C++ to Mathematica. ...
1
vote
4answers
113 views

Build a truncated tower with numbers from 1 to 9 without repeating

consider the image subject to the following conditions appearing in my code, I find not the appropriate numbers ...
4
votes
2answers
116 views

Sorting and keeping the main format of list numbers [duplicate]

I have a list with these elements: list={1/2 (1 + Sqrt[5]), 1, 1, 1/2 (1 - Sqrt[5]), 0}; I want to sort them with ...
4
votes
0answers
93 views

Why does FromDigits transpose its argument (sometimes)?

a = {{1, 2}, {3, 4}, {5, 6}} ; FromDigits /@ Transpose@ a == FromDigits @ a (* True *) The only "strange" syntax I've found in the docs is But it doesn't ...
0
votes
1answer
36 views

Possibly syntax errors? [duplicate]

trying to graph, however graph is blank when i enter it. Please help! ...
0
votes
1answer
326 views

Syntax::sntxf: “…” cannot be followed by “…\MatrixForm” [closed]

I'm trying to create a $3\times 1$ matrix named Pauli but I really don't understand what's the problem of the following code? ...
0
votes
1answer
73 views

How to store value of result in an array for a calculation inside the loop [closed]

Note: In my code I used j (ranging from 3 to 7) but I want j to be general I tried this ...
4
votes
0answers
86 views

“\:”; flagged as syntax error

While answering question 94032, I noticed that Mathematica 10.2 flagged "\:" <> IntegerString[62378, 16, 4] with a red bracket, apparently indicating a ...
8
votes
1answer
172 views

Invalid Symbol Characters

What unicode characters are invalid as a Symbol name? Ideally I'm looking for a complete list. Here is the current list ...
0
votes
1answer
41 views

Evaluation of a Laplace transform for e^-at does not give expected results [closed]

LaplaceTransform[E^-at, t, s] That is my input, and the output I am expecting is 1/(a + s), but I am getting ...
4
votes
0answers
103 views

Multiple Constrained Sum

I need to perform a multiple summation, that obeys some conditions. This arises in the study of a statistical physics model. q=Exp[-β]. I would like to ask if ...
7
votes
1answer
164 views

Why is Reap result nested? [closed]

A minimal (toy) example for my question: i= 1; Reap[Do[Sow[i = (i + 1)^2], {4}]] (* {Null, {{4, 25, 676, 458329}}} *) I presume the entire result is a ...
7
votes
1answer
145 views

What kind of creature is h[c] for definition h[c_][x_] := (* function of x and c *)

To implement "Hero's Method" for approximating $\sqrt{c}$, one iterates the function (x + c/x)/2 for a given number c (e.g., ...
1
vote
1answer
64 views

Display a triangle that rotates at certain rate when space bar is held down?

This question is a follow up on: Open a pop up window that runs a calculation in loop until it is closed? How can I open a pop up to show a picture of a triangle that rotates by ...
3
votes
1answer
78 views

Open a pop up window that runs a calculation in loop until it is closed?

How should I construct a code which opens a pop up window, displays a constantly updating image in it and is terminated once the pop up is closed? The constant updating would be an infinite loop of ...
0
votes
1answer
214 views
2
votes
1answer
45 views

How to use MakeExpression in terminal?

This is in continuation to the question in Infix form of PutAppend ( >>> ) does not work with variable. I was trying to use ...
1
vote
1answer
115 views

Summation over list elements

As we know, one of the simplest way to do a summation (with special intervals) over list elements is using Sum[list[[i]], {i, 3, 8, 2 }] (*with steps of 2*) for ...
12
votes
1answer
605 views

When to use @@@ vs. /@ [duplicate]

So much thanks to Szabolcs in improving sequence.. for complete explanation. I am so glad to read all explanation which fundamentally remove the problem. But in number 4 of its explanation pointed to ...
13
votes
1answer
278 views

ToExpression processing errors

Is their a way to get a more comprehensive return value when running ToExpression? For example when I run ...
5
votes
3answers
249 views

How to imitate list comprehensions for constant arrays?

In Python, ['a'] * 10 generates ['a', 'a', 'a', 'a', 'a', 'a', 'a', 'a', 'a', 'a'] and ...
4
votes
1answer
99 views

How to define UpValues of NBSpline when the length of argument is unknown?

I mimic the built-in BSplineBasis[] to build a user-defined function NBSpline[], Namely, ...
1
vote
0answers
356 views

How can I solve the 2D Laplace equation with Neumann boundary conditions? [closed]

I would like to solve the following boundary value problem for $u(x,y)$: PDE $\quad \quad \frac{\partial^2 u}{\partial x^2} + \frac{\partial^2 u}{\partial y^2} = 0$ Domain $\quad \quad 0 \le x \le ...
1
vote
2answers
147 views

How to define a sequence of piecewise functions and then plot them altogether?

The following is the piecewise functions I want to define ${f_k(x)} = \left\{ {\begin{array}{*{20}{c}} {\frac{{j - 1}}{{{2^k}}}}&{\frac{{j - 1}}{{{2^k}}} \le f(x) \le \frac{j}{{{2^k}}}}\\ ...
20
votes
1answer
258 views

New AssociationThread forms in 10.2?

Bug introduced in 10.2.0 and fixed in 10.3.0 (The extension of AssociationThread is not (yet) implemented and the corresponding documentation has been removed) ...
4
votes
0answers
63 views

String option names for Cells

They seem to be correctly interpreted. I'm asking because of some minor reasons and a major one: NotebookWrite a Cell with WholeCellGroupOpener option I don't know any official confirmation so let ...
2
votes
2answers
99 views

Simplify set-theoretic expressions [duplicate]

As I can get set-theoretic simplifications of expressions and corresponding Venn diagram for example ...
1
vote
0answers
41 views

Mathematica Workflow [duplicate]

What methods/tools/tips have you found that dramatically improved your Mathematica workflow? I have a love/hate relationship with Mathematica. It is useful no doubt, but defies my intuition at every ...
0
votes
1answer
114 views

How to enter piecewise functions into Mathematica [closed]

I'm trying to enter a piecewise function (named eq30) into Mathematica. However, it seems not to work. The expression I entered is ...
0
votes
1answer
53 views

A question about the syntax [closed]

I have $3$ elementary questions to ask and I thank you in advance. Question N°1. What is the right syntax for $$y\equiv0\pmod {2}$$ in the code below? ...
6
votes
2answers
174 views

How to Write Partition with Infix?

The documentation says that using Infix ~, the following input f[e1,e2,e3,...] can be rewritten as ...
6
votes
1answer
88 views

What is the role of _ in this expression?

I'm fairly familiar with basic Mathematica, but some of its more advanced syntax (especially certain special characters) eludes me. In the Scope section in the documentation of ...