12
votes
1answer
183 views

Non Standard Eigenfunction Plots of the Laplacian Over the Unit Square

I have recently been plotting eigenfunctions of the laplacian over the unit square using the NDEigensystem command. However, I have noticed something in the plots ...
6
votes
2answers
218 views

How to test whether a function is positive over the entire range of an interval?

I would like to test whether a function is positive over a given interval. Say I have f[x_] = -x^3 + x^2 + 7*x and wanted to know whether it is positive for all ...
7
votes
2answers
63 views

How to Add a PageBreak menu by MenuSetup.tr

In 1998 there was a discussion on comp.soft-sys.math.mathematica how to add am PageBreak menu to Mathematica. I used the recipe from there for very long time (in fact, I used Mathematica 4 till ...
2
votes
0answers
37 views

No Way to paste a Picture from Clipboard under Linux?

As far as I remember, on a Windows PC in the old days of Mathematica 4 I could paste an image from the clipboard by just pressing Ctl-V. This seems to be no longer available on my Linux PC. If I try ...
0
votes
0answers
50 views

Exporting a plot destroys plot style [on hold]

I have a plot with $x$ and $y$ error bars, and when I export it with the Exportfunction Mathematica ignores the plot styles, so the quite small error cross does not ...
0
votes
1answer
64 views

How to plot the following function?

Say I have a function f(x,y,theta,xi) = x*y*c*theta*xi; where c is a function of theta ...
0
votes
0answers
29 views

Why the plot of derivate to integrate is not same with integrate to derivate? [closed]

ListPlot[Table[-((2 x)/(1 + x^2)^2), {x, -2 Pi, 2 Pi, 0.02}], PlotRange -> All] (*1*) We know that ...
8
votes
2answers
99 views

Slice a mathematica image into sub images along black straight lines?

I have a tic tac toe board I want to dynamically process in mathematica to have my robot play a user in tic tac toe. In order to determine the users move, I want to slice the board into 9 images, ...
3
votes
1answer
49 views

Move framed label alongside y-axis

Maybe the answer to this question is trivial but I am stuck with my last modification for hours now. In my plot i added framed labels to add a certain distance of the labels from their axes. This ...
0
votes
1answer
159 views

How can I solve a 3D heat transfer partial differential equation? [closed]

It's a problem about heat transfer. Here is the equation : Is it solvable using this software? Edit Sorry, I'm new to Mathematica. I have the following code for this problem ...
0
votes
0answers
21 views

Gap Test for Random Number: Especial Case [closed]

how many gaps can i consider for a number like |0.10121|?? Im using the gap test by digits, so for this number i consider 3 gaps or only one??
4
votes
1answer
135 views

How do I disable that Mathematica orders terms in lexicographic order?

I have matrices with entries where the order of the entries is important. Unfortunately Mathematica resorts terms in products in a lexicographic order. For example, ...
2
votes
1answer
113 views

Manipulations with options

I have two functions with options, for example f and g ...
2
votes
1answer
83 views

How do I find the analytical roots of this polynomial? [closed]

I want to find the analytical roots of this polynomial - x - a^3*x*(a^2*x*(a*x*(x - 1) + 1)*(x - 1) + 1)*(a*x*(x - 1) + 1)*(x - 1) ...
1
vote
1answer
53 views

Cross product of three vectors

I am following the answer of Jens from following post: How do I simplify a vector expression? vec /: Cross[vec[x_], HoldPattern[Cross[y__]]] := I want to create ...
1
vote
0answers
39 views

x and y axis nonlinear error fit possible? [duplicate]

I have a set of datapoints with x (position) errors as well as y (measurement) errors. Is there a way in Mathematica to fit a nonlinear function through this points, with weighting both, the x and y ...
3
votes
1answer
95 views

Plotting a finite series w.r.t. a parameter [closed]

So I would like to plot the series below: $$ S_q = k \frac{1-\sum_{i=1}^{W}(1/W)^q}{1-q} $$ where $k$ is a constant which I assume for now to be equal to 1 and $q \in \mathbb{R}$. However, for my ...
2
votes
1answer
105 views

Problem with Volume [closed]

A bug probably. This should give the volume of the unit sphere: vol = Volume[{1. r, th, ph}, {r, 0, 1}, {th, 0, Pi}, {ph, -Pi, Pi}, "Spherical"] but it gives: ...
12
votes
1answer
129 views

How to count the number of the tube

There is a picture Get the binary image binimg = ColorSeparate[img][[2]] // Binarize[#, 0.25] & // Thinning Visulize the result of regconization ...
0
votes
0answers
61 views

Step size control in DSolve or NDSolve [closed]

I have the following differential equation sol = NDSolve[{y'[t] == y[t] - 2*Exp[-t], y[0] == 1}, y, {t, 0, 10}] Plot[y[t] /. sol, {t, 0, 4}, AxesLabel -> {"Time--->", "y(t)--->"}] how to control ...
4
votes
0answers
125 views

Finding eigenvalues in Mathematica: why so slow?

I am trying to find the eigensystem of a large sparse real symmetric matrix, and I only need the lowest 40 or so eigenstates. The relevant code is as follows: ...
3
votes
2answers
115 views

How to integrate on bezier function?

I have: points = {{0, 100}, {250, 0}, {0, 300}, {500, 500}} And I want to know the area below the curve, so I came to: ...
0
votes
0answers
48 views

frequent slow evaluations for trivial expressions, large memory loaded

After loading a lot of data into memory and evaluating several hundred expressions without any problems, trivial expressions such as (1+2) take about 5-10 seconds to evaluate. Sometimes they are ...
1
vote
1answer
37 views

How to correctly use FormulaData

I am exploring some of the functions involving units and formulas, and wondered how to input quantities if the variable has a subscript. This works ...
3
votes
1answer
54 views

Angle between two vectors in spherical coordinates [closed]

I have two vectors: H = {1, 0, π/4}; EA = {1, 0, 0}; Which I want to be in {r, Phi, Theta} - which would should give an angle between the two vectors as ...
1
vote
0answers
30 views

How to import/export to libsvm?

Under the hood Mathematica uses libsvm, so I don't think this question is beyond the pale. I need to export an svm I trained with Classify to the standard SVM Format (which is readable by libsvm). ...
-3
votes
0answers
30 views

Calculate the error and errorbar [closed]

How can I calculate the error for example below and then plot errorbar?
1
vote
2answers
123 views

How to find adjacent polygons of a specific polygon in a VoronoiMesh?

I have developed a code for VoronoiMesh. I am also able to find the polygon with highest number of adjacent polygons. How do I find the indices of the adjacent ...
1
vote
1answer
40 views

Get Isotope Data and Electron Mass in Same Units - kg and Kilograms

I'm trying to find the nuclear mass of $^{238}\text{U}$. To do this, I subtract the electron mass from the atomic mass. I'd like to find the final answer in kilograms. I'd also like to use ...
4
votes
1answer
70 views

Grayscale Morphology

How can I achieve grayscale morphological operations on 2D images in Mathematica. With morphology I mean operations like Dilation and Erosion. With grayscale I mean the operations that take images and ...
4
votes
2answers
85 views

How can I make this code to count Hamiltonian paths faster?

I have this very basic code to count Hamiltonian paths in a graph: ...
2
votes
1answer
88 views

working hours and negative time [closed]

I have a list of TimeObjects. I want to subtract 5h from each element and if TimeObject < 5h then give a negative hour. My ...
6
votes
1answer
99 views

Using two rules for the same variable

I am a newbie in the field so please not angry. I am reading the tutorial below and having a problem. Link: How to Create and Use Rules From the link: If you give two rules for the same ...
10
votes
1answer
67 views

Arrows from GraphicsComplex not converted to Normal form correctly

Bug introduced in 7.0 or earlier and persisting through 10.3.1 or later Show @ Graph[{1 -> 2, 2 -> 3}, Frame -> True] Normal @ % Is this a pure bug, ...
3
votes
2answers
45 views

Thickness of bars in a histogram

How can I control the thickness of the bars (here vertical lines) in a Histogram plot? For example in the plot below (of the corresponding image: ...
0
votes
1answer
39 views

Deciphering Coding Shortcuts [duplicate]

I'm having trouble deciphering why the following couple of expressions evaluate the way they do. #&@@ This returns the first value of a list. Why? Naïvely I ...
0
votes
3answers
67 views

Constructing an arbitrary dimensional matrix with a certain rule

I want to construct the following matrix $M$ of dimension $(N+1)\times(N+1)$ with the following rule (for arbitrary N). Below, in the subscript, as usual, the 1st index gives the row and the second ...
2
votes
1answer
31 views

Encoding/Decoding matrices as integers, integers as matrices [closed]

I want to convert large binary matrices of m x n dimensions into integers, and then to convert these integers to the original matrices. I attempted the following: ...
0
votes
0answers
29 views

DeleteDuplicate from a list with {x == y, y == x} -> {x == y}; [duplicate]

How can I tell Mathematica that it should delete equal elements from a list, which aren't in the same order. For example list={x == y, y == x} ; should become ...
3
votes
1answer
38 views

Interval arithmetic for DawsonF (or other special functions)

I am currently trying to estimate a complicated expression involving DawsonF using interval arithmetic. The interval arithmetic is partially supported by ...
1
vote
1answer
31 views

Formatting the prime factorization of expressions

I have a series expansion in $x$ and $a,b$ are constants which I want to type in $LaTeX$. But the numbers/integers are pretty large (have a lot of digits) so it becomes a bit messy in $LaTeX$. ...
-1
votes
0answers
18 views

Compile function with array argument and Listable runtime attribute [closed]

How to create a compiled function with an array argument and listable runtime attribute? I've tried ...
0
votes
1answer
34 views

Exists[ ] statement inside RegionPlot[ ] too hard to resolve?

I've got a very complicated existential boolean expression, call it $\exists x: condition$, involving variables $p, q, $ and $x$. Is there a way to plot the region in which this statement holds ...
1
vote
1answer
35 views

ListPlot3D Link Tick Range to color gradient

i am pretty new in Mathematica but upt to now i am nearly done with my first higher plot. I just want to use the whole range of my 7 z-values linked to the 7 colors in my defined blend for #3 (z) ...
0
votes
0answers
21 views

Rewriting List of Matrix Equation in Terms of Individual Equations? [duplicate]

I have a list of matrix equations M1={{a1,b1},{c1,d1}}; A1={{x1,y1},{z1,w1}}; M2={{a2,b2},{c2,d2}}; A2={{x2,y2},{z2,w2}}; sys={M1==A1,M2==A2}; which I would like ...
0
votes
0answers
43 views

What is the meaning of #, Root and & [duplicate]

I am new, but can any one tell me what is the meaning of formulas of x and y in the picture?
1
vote
1answer
44 views

Coordinates of the centers of the triangles composing a Koch snowflake [duplicate]

Let's suppose we have a Koch snowflake of arbitrary initial side length $a$, and a Cartesian coordinate system whose center coincide with the center of Koch snowflake, as shown in the figure. How ...
4
votes
4answers
171 views

Applying rules to expressions [closed]

I'm trying to write a rule that acts on any number, lists, expression and so on to turn any negative numbers positive. The simple r = n_ -> Abs[n] works ...
9
votes
2answers
92 views

Unexpected view of the Comsol result when I postprocess it in Mma

I simulated some nonlinear PDE using Comsol. Here one can find the results u=u(x,y) in the form of an Excel table with the terms ...
4
votes
0answers
56 views

Create an adequate 'training set' to train a ClassifierFunction which performs the role of the built-in `SubsetQ`

I am trying to "grow" my own SubsetQ function using Machine Learning methods. My cSubsetQ when given two lists (listA and ...

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