2
votes
2answers
544 views

How to remove a singularity with WhenEvent

Bellow I have a differential equation which hits a singularity at low values of t. What I want to do is somehow utilize the WhenEvent command in order to replace ...
0
votes
1answer
355 views

Avoid trigonometric simplifications?

When evaluating the expression Sinh[x]^2 + Cosh[x]^2 // FullSimplify I get Cosh[2 x] That is indeed a simplification, but ...
0
votes
0answers
203 views

Finding all roots of the system of two complex equations

I need to find all roots for the system of two complex equations. Obviously I can rewrite them as 4 real however problem remains. I have looked through routines connected with using ContourPlot ...
5
votes
1answer
192 views

Style of Slideshow

So I am giving my first shot at making a Mma slideshow. But I am finding difficult to change the formatting of Sections and others in the slideshow. I can change the style of Sections in the Working ...
-4
votes
1answer
203 views

Problem with interpolation

I have a problem with the function interpolation. when I use it my points are all very shifted. Do you have an idea of the solution? ...
9
votes
2answers
859 views

Font sizes in graphics

I'm trying to find an explanation for the different sizes I'm seeing for fonts added to graphics in different ways, and haven't yet located an easy to understand explanation. Here's a minimal ...
0
votes
0answers
21 views

Conflict among Permutations and Graph utilities once Combinatorica is loaded [duplicate]

I have tried to figure out and solve the problem of compatibility of Permutations and Graph utilities of Mathematica once the Combinatorica Package is loaded, but I failed :(. Could anyone explain me ...
0
votes
1answer
103 views

Plotting query - same values on Y-axis / viewing data

I'm new to Mathematica, and have numerically solved two similar functions with the following code; ...
3
votes
3answers
103 views

How to use Show in case one of the graphics doesn't exist?

I tried to combine three and more graphics with the Show command; but sometimes there is no data, so some of the graphics are empty lists. I tried this: ...
12
votes
3answers
516 views

Simulate a simple spinner

I'm teaching some simple ideas in probability to students in grade 7. The "spinner" below works, but I'm wondering how I could make it just a bit more realistic by having it actually "spin" around a ...
11
votes
1answer
291 views

I can't use PatternSequence with Cases

I have a list of integers: s = {4, 5, 5, 6, 2, 5, 3, 2, 4, 2, 1, 1, 4, 3, 4, 3, 1, 6, 3, 4}; And if I do this, both occurrences of 4 after 3 are replaced. ...
0
votes
2answers
277 views

characteristic polynomial based on differential equation

I have this differential equation: $$\ddot{x}-\frac{1}{6} \dot{x} - \frac{1}{6}x = e^t$$ When I DSolve it looks like this: ...
3
votes
0answers
112 views

rule transformations for compositions of tensor products

The tensor product satisfies far commutativity: $(f \circ g) \otimes (h \circ k) =(f \otimes h) \circ (g \otimes k)$. I have some replacement rules I'd like to apply to an expression containing ...
24
votes
3answers
1k views

How to find the center of a circular pattern?

I am writing an algorithm that finds the center of 500 x 500 pixels images coming from a live feed from a camera at 50 Hz. So it has to be quick! The images are images of an optical field which looks ...
2
votes
1answer
221 views

Simplify expression to Abs

FullSimplify[Sqrt[1/(a^2 b^2)], Element[{a, b}, Reals]] gives Abs[1/(a b)] How do I simplify the following expression ...
1
vote
1answer
416 views

Method used by FindFit

Using FindFit, Mathematica selects an optimal algorithm when Automatic is selected. I'd like to know the name of the method ...
4
votes
1answer
394 views

How to get confidence bands of parameters from a fitting procedure?

I have done fitting of data points with a given model that has two parameters (A and B), using NonlinearModelFit. The result of the fit is the maximum of the ...
2
votes
3answers
438 views

Why doesn't Mathematica plot $n(-1)^n$ with Plot?

I was in doubt if this question should be asked in Mathematics.SE or Mathematica.SE, but I've decided this site would be more appropriate, because I think those who read my question here will know ...
4
votes
1answer
182 views

Access curated or locally stored data with curated data functions?

Say I have a toy package, something like: ...
3
votes
1answer
872 views

Accessing Twitter API using Mathematica [duplicate]

How do interact with the Twitter API using Mathematica? SocialMediaData is a lovely function, but appears to be severely limited in what it can draw from Twitter. For example, if I want to get a list ...
2
votes
2answers
602 views

How to expand a general expression in cross and dot product in Mathematica

I am looking for a way to simply the general expression in cross product and dot product with general vectors. I got a help in How do I simplify a vector expression? but soon I find that it doesn't ...
2
votes
2answers
124 views

changing a symbol into a function variable

Struggled for a while on this problem and hopefully you can help... I have a mathematical expression that currently has a symbol where I used to have a function variable. How do I make the symbol ...
-1
votes
1answer
105 views

Sorting the element in a PDB text file

I am a new user of Mathematica and currently using version 9. I want to rearrange the element of one PDB text file with respect to another PDB text file. Suppose I have a PDB file like this: ...
2
votes
1answer
392 views

NDSolve complains about missing derivatives of dependent variables in Mathematica 9

In Mathematica 8 NDSolve[{x[t] == 1, x[0] == 1}, x[t], {t, 0, 10}] solves fine and returns ...
1
vote
2answers
227 views

build and estimate a time series process

I want to generate an EGARCH process. My problem is that I do not see how to create new processes beyond those available. The process itself is : $$\epsilon(t) = \sigma(t) \eta(t)$$ ...
1
vote
3answers
235 views

Minimize user defined function

I have a user defined function h[i_,j_] and I would like to find its minimum value over all integers $1 \leq i \leq 100$ and $1 \leq j \leq 100$ and $j \leq i$. I would just like Mathematica to try ...
15
votes
2answers
1k views

Fastest way to measure Hamming distance of integers

I am looking for a fast and robust way to calculate the Hamming distance of integers. The Hamming distance of two integers is the number of matching bits in their binary representations. I expect that ...
6
votes
2answers
335 views

How can I find if the number of subsets for a list is very large?

I'm trying to find the following; Subsets[Range[2, 2300], {4}] but my computer gave the following error: ...
10
votes
1answer
291 views

Why does Mathematica fail to series expand this simple expression?

I wanted to expand the function $(x+2)^{x+2}$ around $x = -1$, that is, using Series[(x + 2)^(x + 2), {x, -1, 2}] and Mathematica returns the same expression. ...
1
vote
0answers
35 views

How to implement a set method? [duplicate]

I'm trying to program using object orientation in Mathematica. For this i need to implement get and set methods. Lets consider that we are working with a person class, that have the fields name and ...
4
votes
1answer
162 views

How can I monitor and detect when a website has changed?

I'd like to detect when a website has changed, in particular when new products are announced on a site that doesn't change to often. Here's the code I wrote but I don't think it is perfect. Also the ...
27
votes
1answer
518 views

How can I make threading more flexible?

Threading automatically with Listable functions requires the argument expressions to have the same length (or for one of them to be atomic). For nested lists the ...
6
votes
0answers
109 views

Design considerations behind `O` (a.k.a. BigOh, a.k.a. Landau Order)

This works without any warnings: O[Log[x]]. This raises a warning: O[x^2]. I have a few questions around this: Why is it a ...
0
votes
2answers
211 views

Formatting results of integral approximation methods comparison.

The integral is Integrate[Sqrt[1+x^3], {x, -1, 1}]. I want to create a Table with three columns and four rows that shows the ...
1
vote
2answers
242 views

Computing distance matrix for a list

Using functional programming in Mathematica, how can I compute a distance matrix for every element in a list of matrices... The distance would be computed between the item in the list and a "target ...
3
votes
3answers
235 views

Logical AND operation over several comparisons

Let x and y be arrays defined as Array[x, m], Array[y,n] respectively. How to generate the following function of $x$ and $y$ for variable $k$: ...
3
votes
1answer
339 views

Issues with ColorFunction Scaling when using RegionFunction in VectorPlot

I was plotting a VectorPlot and restricting it to the physically meaningful region using RegionFunction. To my surprise, the ...
0
votes
1answer
274 views

Solving a system of equations using subscripted variables

I want to solve this equation: X(i, j) + C*Y(i, j) = Z(i, j) Where ...
5
votes
2answers
134 views

Trouble with Replacements [duplicate]

I have the following line of code: Plus @@ Table[p[x], {x, 0, 20}] /. p[x_] -> Boole[MemberQ[{0, 5}, x]] The first part of this produces ...
4
votes
1answer
541 views

How can I efficiently write formatted data to a Gaussian Cube file?

I am working with data files that contain information about electronic wave functions. The data format is specified by the quantum chemistry program Gaussian. I need to import the data, manipulate ...
9
votes
4answers
1k views

Problem with ContourPlot

I tried these ...
3
votes
1answer
267 views

Including two ListLinePlots in a 3D graphic

I have two lists of data which I am plotting on two ListLinePlots. I would like to have these two plots appear perpendicular to each other on a 3D graphic. I have ...
0
votes
0answers
32 views

How does Plot evaluate its argument? [duplicate]

I have a list of about twenty InterpolatingFunctions that I'd like to plot. They are interpolations from experimental data (frequency spectra between 100 and 5000 ...
6
votes
1answer
167 views

RSolve[{y[0] == y0, y[t + 1] == (1 - (t + 1)/100) y[t]}, y[t], t]

When I evaluate this code: RSolve[{y[0] == y0, y[t + 1] == (1 - (t + 1)/100) y[t]}, y[t], t] I get an RSolve::bvnul error. I don't understand why. Yet, if I ...
5
votes
2answers
180 views

Why does Integrate return a solution that is not defined at a particular point when it actually is well defined at that point?

I am trying to compute Integrate[Sqrt[x^4 + (y - y^2)^2], {x, 0, y}] Mathematica 8 gives ...
12
votes
3answers
545 views

How to program a F::argx message?

How useful is it to program a user-built function in a package to produce a red warning message F::argx if you give the wrong number of arguments to that function? ...
4
votes
1answer
325 views

substitution rules for Penrose tiles

This page on W|A shows a nice substitution rule to draw kites and darts. I'd like to implement the rule in Mathematica, so I've drawn the original kite and its replacement (separately). I've also ...
2
votes
1answer
174 views

diff-able text-only notebooks?

I would like to save my Mathematica notebooks as plain-text documents, so that I can keep them under git version control. I thought that ...
7
votes
2answers
112 views

How can I recover a graph from a graphical output in a notebook after resetting the kernel?

I have an old Mathematica notebook with an output for a graph structure $G$ I would like to recover. However, the routine for building up the graph is stochastic, so I can't simply rerun the code. ...
1
vote
1answer
103 views

given n lists, get list of applications of function to n-tuples

Is there a built in function or an easy rule to do the following transformation? H[{A[0], A[1], ...},{B[0], B[1], ...},...] into ...

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