1
vote
1answer
23 views

How to distribute PermutationProduct over the sum

Assuming I have two elements of the permutation group algebra $a_1$, $a_2$ such that $a_i=\sum_{p\in S_n}\alpha_pp$, I want to define a linear product $\odot$ that distributes over the sum and pulls ...
0
votes
0answers
19 views

an NIntegrate inside a manipulate in mathematica was working and suddenly won't work now. it says indeterminent and it doesn't make any sense why

my title says pretty much everything heres what I'm entering. NumericQ returns a false value but it was true before. Im loosing my patience because this is so ...
265
votes
12answers
45k views

Where can I find examples of good Mathematica programming practice?

I consider myself a pretty good Mathematica programmer, but I'm always looking out for ways to either improve my way of doing things in Mathematica, or to see if there's something nifty that I haven't ...
4
votes
1answer
60 views

Select cases from a list

I have a list in the form : {1,1,1,0,-1,-1,1,1,1,0,0,0,0,-1,-1} No I'm trying to select only those sequences which start with 1 have a zero (or many zeros) ...
0
votes
0answers
16 views

How to do assignments through MathLink?

In Mathematica I can make the assignment 'foo = bar' with Set[foo,bar]. However, if I try to evaluate 'Set[foo,bar]' through MathLink then it appears that MathLink gets stuck while trying to read ...
-2
votes
0answers
33 views

Issue with Set function

0 down vote favorite Tables often come with column headers. Indexing the columns with the header is a natural thing to do. Although a proper dictionary is the usual solution in such a case, I find it ...
0
votes
1answer
48 views

Matrix Operation

I have a $3\times3$ matrix A, and a function sTrans that outputs two $3\times3$ matrices in a list when given a $3\times3$ ...
2
votes
1answer
176 views

Structure of curated data?

Is there a way to programmatically access the structure of curated data present in Mathematica (for each type of information, for example for CountryData or ChemicalData) that would allow access to ...
0
votes
1answer
28 views

Manipulate executes twice

I need help, guys! Here the script: ...
0
votes
0answers
24 views

“NotebookPredictions”

I have deleted Mathematica user folder, as well as reinstalled Mathematica, but I keep getting error message: The front end encountered an error while processing a "NotebookPredictions" packet. What ...
2
votes
2answers
101 views

How to select the first “lowest” (first valley) number in a list?

I would to select the first valley of the list of coordinates below. It should be {3, 1}. ...
2
votes
1answer
48 views

Generating the set of all strings within a fixed edit distance of a initial string?

Provided a starting string initialString, and a particular alphabet of allowed characters {"A","B","C","D","E",...}, how can I ...
0
votes
1answer
79 views

Getting cdf content from nice Wolfram info graphic

There is a very nice cdf info graphic on the Wolfram Webpage (http://www.wolfram.com/cdf/uses-examples/infographics-full-example.html). I'd like to have a look at the code as I'd like to do something ...
3
votes
2answers
87 views

How do we make a negative integer out of a string of a negative number and vice-versa?

Negative numbers are not taken into consideration by mathematica's built-in functions. FromDigits["-2"] Gives me this message: ...
1
vote
2answers
99 views

X-Y scatterplot

Hi I have a simple question. How do I plot the following with Day 1 as my X axis and Day 2 as my Y axis? I need the 22 variances plotted according to the Day they were taken from (these were ...
-2
votes
0answers
46 views

Shooting method

can someone look at my equations http://imagebin.org/306581 , and tell me how would I simulate it? Any idea would work. I am looking for a start. I have a code in matlab, but its taking vary long, and ...
7
votes
1answer
63 views

Explain the difference between ViewPoint and ViewVector?

I've read the documentation, but am still very unclear as to what the difference is between ViewVector and ViewPoint for ...
2
votes
0answers
42 views

Understanding of method for NDSolve

I used automatic method for NDSolve. Then I asked myself - which method Mathemathica prefered? I got an answer for this question on this forum, that I need to use: ...
3
votes
1answer
54 views

Little triangles appearing in a Mathematica region plot saved in a PDF file [duplicate]

I am trying to produce a region plot of many functions, but Mathematica keeps showing me the little triangles when I save it as pdf. An example: ...
1
vote
0answers
27 views

Conjugate of InterpolatingFunction?

From NDSolve, I got this: {{a1 -> InterpolatingFunction[{{0., 40.}}, "<>"]}} What would be a sensible approach to ...
3
votes
2answers
67 views

Finding all instances of length $N$ common subwords in two strings

Given a pair of strings, I'd like to return a list of all common subwords of a fixed length of "n" characters (i.e. contiguous subwords of length "n" that occur in both strings), allowing for ...
9
votes
4answers
221 views

Efficient way of identifying the indices of first occurrences

It seems to me like identifying the first occurrence of unique elements should take about the same amount of time as it takes to delete duplicates. My data sets are much larger than this (...
0
votes
0answers
50 views

Manipulate for Electric Field

I'm kind of new to Mathematica but I'm getting the hang of it slowly. Anyways, I'm trying to do a project on the electric field of two particles so my professor helped me with this code (sorry in ...
5
votes
0answers
66 views

Strategies to find curves on messy data using FindCurvePath

I have a set of data points that correspond to roots of a transcendental equation with respect to a parameter (the abscissa) which, by the properties of the system, define continuous curves (might be ...
0
votes
0answers
26 views

Find the values of parameters so that the matrix is symmetric positive definite

Good evening , I have a matrix 20x20 in symbolic form. The matrix depends on 5 parameters (a,b,c,d,e). I would like to get the interval of each parameters that ensures that the matrix S is symmetric ...
0
votes
0answers
28 views

Meaning of FourierParameters [on hold]

Many of the Fourier analysis functions take a FourierParameters option. FourierParameters. The documentation just says is an option to Fourier and related ...
6
votes
2answers
193 views

Scan vs Map vs Apply

I cannot understand the difference between Apply, Scan, and Map. I have tried to play with ...
1
vote
0answers
21 views

When to use GenerateConditions->True

Many functions, usuallly those involving integration, take a GenerateConditions option which often defaults to False, or at ...
4
votes
2answers
125 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
38 views

Questions regarding DictionaryLookup of Mathematica

a. Make a function longest[lang_] that gives the length of the longest word in the dictionary of lang. You should get ...
0
votes
1answer
39 views

Loading Statistics`Library`

I need to use a number of functions from theStatistics`Library` namespace. Since that is a bit of a mouthful I would like to import it, but I get errors: ...
2
votes
1answer
34 views

Variable number of nested variable-range sums

I would like to express the following nested sum in Mathematica: $$ \sum_{k_1=m+j-1}^{N-1} f(N,k_1) \sum_{k_2=m+j-2}^{k_1-1} f(k_1,k_2) \cdots \sum_{k_m=j}^{k_{m-1}-1} f(k_{m-1},k_m) $$ where $m$, ...
1
vote
1answer
69 views

Overlay Rectangle on a ListPlot

I have a ListPlot of 100 data points in the range of 0 and 1. Now I'm trying to find a way to overlay (four) rectangles onto the listplot in 0.25 steps horizontally. Essentially I just have BinLists ...
0
votes
1answer
326 views
2
votes
1answer
48 views

Importing data from excel and assigning a variable to each of its columns

How should I assign variables to the data imported from excel containing 3 columns which are time, mean and standard deviation. I want to perform operations on the three variables to get new ...
1
vote
2answers
51 views

How to sort the adjecency matrix of bipartite graph so to have two off-diagonal blocks

In a bipartite graphs there are two class of nodes, say A and B. Each node of class A may interact only with nodes of the class B, and viceversa. The corresponding adjecency matrix is thus composed by ...
0
votes
0answers
33 views

Ticks don't display on Y-Axis of Histogram when using PlotRange

I have a histogram, if I create it without specifying the PlotRange it works fine and the ticks on the Y-Axis are displayed ...
1
vote
0answers
46 views

Solving for a charge distribution from a dipole moment [on hold]

I've been looking around but I haven't been able to find any way of solving this conceptually simple problem. In short I am trying to find the charge density in a dielectric in an external electric ...
0
votes
1answer
106 views

Exporting tables of interpolating functions

A few weeks ago I asked a question about manipulating parameters in NDSolve (Looping with NDSolve?) , and received some very helpful advice about the manipulate environment; now I want to take the ...
1
vote
0answers
68 views

Find lengths of contours in a ContourPlot

I am trying to find the lengths of different contours in the following plot: It is a complicated piecewise function evaluated on the unit disk. I am hoping there is an easy, generalized way to ...
3
votes
2answers
103 views

Finding the parameter that makes real part of an eigenvalue of a matrix 0

I have the following 3x3 matrix: $\left( \begin{array}{ccc} 0.04 -0.4 b & 0 & 0.04 -0.4 b \\ 0 & -0.08-1.2 b & -0.06-0.9 b \\ 1.04 -0.4 b & 2.08 -0.8 b & 0 \end{array} ...
0
votes
2answers
23 views

Expand expression into quotient of negative power series

I have a function T(z) and want to expand it to the following form: At the end I want to have a list of equations, which can calculate a0, a1, a2, b0, b1 and b2 with different values of h1, h2, ...
6
votes
0answers
56 views

Efficient JSON parser for Mathematica

Im looking for a efficient way of parsing JSON data in Mathematica. I am having a lot of problems with ImportString because it uses Java, is too slow, and uses too ...
0
votes
2answers
24 views

How can I troubleshoot a PDF that fails to import?

I'm trying to import a PDF file whose text I'd like to parse, but I'm getting an error with no explanation: ...
1
vote
0answers
67 views

Integrate does not accept my integrand expression

I want to calculate the symbolic integral, but I could not obtain the final results from Mathematica. ...
4
votes
2answers
79 views

Visualization of matrix transformations

I define the "matrix transformation" here as follows: $\left[ \begin{matrix} x_1' \\ x_2' \\ \end{matrix} \right]=\left[ \begin{matrix} a & b \\ c & d \\ \end{matrix} ...
0
votes
1answer
67 views

Configure initial directory

How can I configure the initial directory? By configure, I mean set it so that when Mathematica starts the initial directory is one of my choosing. By the by, what exactly is the significance of the ...
3
votes
1answer
190 views

Create ParametricFunction object without ParametricNDSolve

Documentation of v9 states that ParametricFunction is generated by ParametricNDSolve and ...
1
vote
0answers
63 views

Inhomogeneous phase-portrait with StreamPlot

I have a problem with a must-be simple streamplot. The potential function governing the motion is U, and I have the following code in Mathematica: ...
0
votes
1answer
57 views

Where can I find a dark stylesheet for mathematica?

The default white is very tiring for the eye after some hours.

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