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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4answers
117 views

Help with writing a polynomial series [duplicate]

I want to write and evaluate an expression something like Sum[x[i] Product[y[j], {j(!=i), 1, n}], {i, 1, n}] but with correct syntax, where n is a any number ...
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1answer
215 views

Syntax for integrating over limits specified by a Table

I wish to use NIntegrate to compute multidimensional integrals. However, I don't want to manually input the limits for the dimensions. I want to store the ...
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1answer
123 views

Working of Date[]

Date[] returns the current date of local system, Date[1] returns {2012, 11, 15, 17, 41, 0.3161629}, ...
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1answer
256 views

Compile with array operations

When I use the function f with only the Module ...
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1answer
93 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: ...
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1answer
75 views

Why do two codes give different output?

I have tried the following to get the eigenvalues of several matrices of the type: ...
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1answer
85 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?
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1answer
86 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: ...
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1answer
110 views

Passing f[x][[1]] to FindRoot [duplicate]

FindRoot seems to fail for most examples of the form f[x_?NumericQ] := {x - 3 , x^3}; FindRoot[f[x][[1]], {x, 3}] ...
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2answers
149 views

MapThread with List Manupulation

I have the following three lists: ...
1
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1answer
197 views

Bincounting a list

I'm a Mathematica novice here. I'm trying to execute the following code to add random 1's into a zero matrix, repeat this many times, and then bin/histogram the number of nearest neighbor 1s. Can ...
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2answers
983 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: ...
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1answer
206 views

Can I use Table without the appropriate bounds?

I´d like to use the Table command without defining n, so that I can have a list of n ...
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2answers
46 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 ...
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1answer
49 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] ...
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1answer
191 views

KroneckerProduct and Transpose [closed]

I need to take the KroneckerProduct of the an $n \times n$ identity matrix and a $1 \times n$ row vector (let's call it $T$), both of which are numerical. As in: ...
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1answer
162 views

Correct usage of GeoPosition

My goal is to trace a ray down to the ground. I have done: ...
1
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1answer
224 views

Syntax error: newline character interpreted as multiplication

I'm getting this error in Wolfram Workbench, and I don't know where it comes from: "Syntax error: newline character interpreted as multiplication" This error happens around an If[] function, in a ...
1
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1answer
62 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 ...
1
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1answer
83 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 ...
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1answer
41 views

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

I have a list of Values and a list of variables. I want to set the Values into Variables. Assume the following code: ...
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1answer
205 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 ...
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1answer
228 views

Solve this equation symbolically

I am trying to solve the equation for the quantity r = y/x symbolically: 3/y^4 == 3/x^4 + a/(x + 2 y)^4 with the requirement that we need to perform the ...
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1answer
178 views

Remove failed Solve[] attempts

I can't figure how to replace a failed evaluation with a null value. I am very new to Mathematica. I have an equation that are being processed using the Solve[] ...
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2answers
238 views

How to insert an expression in a Mathematica program?

I need to insert a very large expression in a Mathematica program. So I first Put[large expression,"file"] and then use Block[{}, Get["file"];...] to ...
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0answers
20 views

Syntax error in debug mode

It appears that in debug mode, the \[Piecewise] symbol gives syntax error. Is it a bug? Are there ways to fix that except write it in the input form?
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0answers
56 views

CreateDialog opening two windows instead of one

I'm having issues working with code from Mathematica 9.0.1 since I've updated to 10.0.0. My previous code involved using packages to set functions, and then those packages were loaded and the ...
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0answers
86 views

SyntaxForm not correctly parsed by FrontEnd

When using TagBox with SyntaxForm, I noticed sometimes it is not well parsed by the ...
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1answer
70 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
111 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 ...
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2answers
210 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, ...
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0answers
74 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
37 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
120 views

Defining an operator

Let s be a positive integer and let DifferenceDelta be this function with step = 1. Define ...
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1answer
92 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
103 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
842 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
169 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
133 views

Differences between 'Solve' and 'LinearSolve' [closed]

Using the function 'Solve' I can do the following: Solve[a x + y == 7 && b x - y == 1, {x, y}] I get the following output: I want to get the same output using 'LinearSolve' instead. How ...
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1answer
92 views

How do I plot a Taylor polynomial of various degrees in two variables? [closed]

I want to plot the Taylor polynomials of $f(x,y)= Sin(1 + x + y^2)/(4 + x^2 + y^2)$ of degrees 4 and 7 around the point $(0,0)$ over the rectangle $[-\pi,\pi]\times [-\pi,\pi]$ I am currently using ...
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1answer
370 views

Why is EigenValues returning Root expressions?

This is the code I have: ...
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2answers
64 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 ...
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1answer
77 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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1answer
100 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
123 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: ...
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1answer
486 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
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1answer
345 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 ...
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2answers
86 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
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1answer
66 views

Moment generating function for custom distribution [closed]

For some reason the following fails. I tried everything I could, and I don't know what else to try. ...
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1answer
155 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]. ...