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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0answers
50 views

Using Nearest on a 2D List (seeing extra parentheses)

I am working a problem involving colliding particles. I define a list of particle diameters (effectively a bin distribution). I need to know if two particles collide, in what bin diameter should I ...
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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
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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 ...
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0answers
193 views

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

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 ...
1
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2answers
326 views

Changing Default Color for Titles, Sections, Subsections, etc., and Items (bullet color) [duplicate]

I'm new to Mathematica 9, and I assume there must be an easy fix for my problem, but I have not been able to find any yet. Essentially, I want the default color for the text of all of my titles, ...
1
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0answers
77 views

Decapitating “explicit” and “implicit” heads

This is a follow up to this question. So far, I named "explicit" heads to those that appear explicitly in the expression. For example, f[x] has an explicit head. I ...
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0answers
42 views

Matching Root[…] objects with patterns, unexpected hidden argument

I needed to write patterns that could distinguish between arbitrary-function and polynomial forms of Root objects, for example, ...
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0answers
138 views

Defining an operator

Let s be a positive integer and let DifferenceDelta be this function with step = 1. Define ...
1
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1answer
102 views

How to programmatically comment out multiple source files?

How to programmatically comment out the entire content of multiple .m source files assuming they start with correct Mathematica syntax? I need it to be robust so ...
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1answer
127 views

When is Evaluate needed within function arguments? [duplicate]

I'm trying to do a simple variable substitution within a ContourPlot, but it's not working. Here's an example: ...
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2answers
1k views

Why function cannot be defined inside For loop? [closed]

I have a following code (which is simplified version of what I am doing): For[i = 1, i <= 5, i++, f[x_] := Sin[x]^2 Print[{i, f[i]}] ] And the question ...
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1answer
188 views

Please explain this code (contains Append, Do, Coefficient)

I am a graduate student using a past student's Mathematica program. Will someone please explain to me exactly what this piece of code is doing? Specifically the ...
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1answer
105 views

Can't get a plot from piecewise parametric function [closed]

I can't seem get a 3D plot from r[t]. Any suggestions? ...
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votes
2answers
75 views

Referencing elements of ArrayRules

How do I call elements of ArrayRules by their indices rather than by Part[ArrayRules[list],i]? I'd like to call the element that ...
0
votes
1answer
103 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
2answers
81 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 ...
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: ...
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votes
1answer
118 views
0
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1answer
148 views

Normalize equation in NDSolve?

I have numerically solved and plotted the solution to the Mathieu equation using NDSolve successfully, as below: ...
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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: ...
0
votes
1answer
709 views

What is wrong with this Cobweb plot [closed]

Something is wrong with my cobweb plot code but I couldn't figure out where do the mistakes come from. So basically we have the iterative map $x_n == x_{n-1}^{2} - 3 \mu$. I would like to draw a ...
0
votes
1answer
511 views

Mathematica command for type checking?

I have a program where users can enter mathematica commands that can evaluate to any of the standard numeric types (complex, real, int, etc.), or to boolean values. Moreover the users can enter ...
0
votes
2answers
111 views

Getting value of clock [duplicate]

I have the following code: a = Dynamic[Floor[Clock[2]]] (*So this basically alternates between 0 and 1*) If[a==1, Print["true"]] But this doesn't work, it ...
0
votes
1answer
50 views

Compile decreases the number of returned list elements

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

Function input syntax [closed]

My functions are ...
0
votes
2answers
64 views

For Loop in Mathematica {n, factored form of x^(n)-1} for 95<=n<=105

I am new to mathematica. I am trying to write a for loop to print out {n, factored form of x^(n)-1} for 95<=n<=105. I have followed the directions of another for loop, and gotten the following ...
0
votes
1answer
323 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]. ...
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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: ...
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1answer
342 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: ...
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1answer
87 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, ...
0
votes
1answer
139 views

How to tell Mathematica to make assumptions? [duplicate]

Say I want to integrate 1/(x^2+a^2) and I want Mathematica to know that $a>0$. What would be the command? Something like: ...
0
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1answer
109 views

Convert code from C++ to Mathematica [closed]

I need to know how to convert the following code in C++ to Mathematica. ...
0
votes
1answer
51 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 ...
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votes
1answer
67 views

How do I apply a conditional append rule to plot randomly chosen points?

I'm working on an attempt at forming a sort of "Mandelbrot" set using Newton's method and randomly chosen points. Effectively I need to define a loop for Newton's method to determine whether my points ...
0
votes
1answer
63 views

Fastest way to make division between a number and elements in a list [duplicate]

I have a list y={{a,b},{c,d},...} of dimension {10^5, 2}, and number x. I want to divide only the second part of each element of the list by x, and have as result a new list {{a,b/x},{c,d/x},...}. ...
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votes
1answer
39 views

Full superset not displayed on Manipulate slider

I wish to incorporate ODE solution with Bondary condition sets: ...
0
votes
1answer
225 views

Getting “Null” output from package?

I have a script written to test a package as follows: ...
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 ...
0
votes
1answer
80 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; ...
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votes
1answer
146 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' ...
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1answer
90 views

Plot producing many error messages when given complicated function

I'm new to Mathematica and am running in to all sorts of silly difficulties with coding in it. I'm trying to calculate a function f[x, k], normalise it with another ...
0
votes
1answer
221 views

Pattern match with Table for matrix dimension check

In Mathematica, often an expression involving matrices will encounter dimension mismatch errors, like we are multiplying a 3x2 matrix to a 3x4 matrix. Below we define a new symbol Dim, which can be ...
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votes
1answer
233 views

How to generalize a formula?

This is a piece of my code: ...
0
votes
1answer
54 views

What does the syntax <<X>> mean? [duplicate]

What does the syntax; << X >> mean? Where X is a number? Cheers
0
votes
1answer
144 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
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 ...
0
votes
1answer
51 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? ...
0
votes
1answer
40 views

Testing Conditions in For Loops

I am attempting to create a set of coefficients that satisfy a set of conditions using the Do function and If statements. I did this successfully with a basic set of conditions: ...
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1answer
250 views

How To Use D[ ] to Define a System of PDEs

We have two variables $u_{1}$ and $u_{2}$ which are functions of $x,t$. That is, $u_{1}=u_{1}(x,t)$ and $u_{2}=u_{2}(x,t)$. Consider the the system of partial differential equations $$\frac{\partial ...