All Questions

1answer
90 views

How do you refine the elements of a 3D mesh?

Response to Answer below. Original Question: I am trying to refine a 3D mesh in a certain region. This seems relevant but does not work for me. I start by making the region which consists of a box ...
1answer
34 views

Looping over a function with several parameters

Folks I am a beginner in Mathematica and have a simple question regarding loops: Here's the problem, I have a dataset of with four columns and I need to loop over each row. So the matrix in which my ...
0answers
54 views

What's inside Dataset? [duplicate]

It seems that Dataset has rich structures in them, for example: ds = Dataset[{<|"a" -> 1, "b" -> "x", "c" -> {1}|>}]; TreeForm[dataset] Could ...
2answers
727 views

Why is Mathematica destroying this graph?

Here I have a picture of a function I graphed: reg[x_,y_]:=(x^2+y^2)Cos[4ArcTan[y/x]]; Plot3D[reg[x,y],{x,-2,2},{y,-2,2},AxesLabel->Automatic] And here is ...
0answers
61 views

Can a single Sum with multiple iterators be different from nested Sums?

Multiple sums are documented with two or more iterators, for example: Sum[1/(j^2 (i + 1)^2), {i, 1, Infinity}, {j, 1, i}] however the same answer can be ...
1answer
30 views

Export a 3Dplot keeping the zoom, rotation properties

I want to export a 3Dplot but when I export the image remains quiet. I want to the image can rotate and make zoom and paste in to a Powerpoint, for the presentation I can explain to the public the ...
2answers
154 views

How to access Dataset's metadata

A Dataset object has internal metadata. For example, let ds = Dataset[{<|"a" -> 1, "b" -> "x", "c" -> {1}|>}]; ...
1answer
47 views

Find numerical solution to this system of DE

I am trying to solve this system \left( \begin{array}{ccccc} 2 k & -k & 0 & 0 & 0 \\ -k & 2 k & -k & 0 & 0 \\ 0 & -k & 2 k & -k & 0 \\ 0 & 0 ...
2answers
39 views

Solving several inequalities in Mathematica

I am a very beginner of Mathematica and the following will probably be a very stupid question. I have a bunch of inequalities in 6 unknowns and I want to find the set of values satisfying them. Can I ...
0answers
5 views

Prove that the converse of a strong digraph is also strong [migrated]

I would like to know how I prove this. The converse of a digraph D is obtained from D by reversing the direction of every arc of D. Show that a digraph D is strong if and only if its converse is ...
1answer
64 views

Plotting 3-vectors over a 3D lattice [closed]

I am trying to plot a magnetic structure, which is basically using Mathematica to read and plot a .dat file. In the file, each row which has six numbers, the first 3 represents the atomic postion, and ...
0answers
42 views

Is there any point to using a variable as a function parameter?

Normally one only sees patterns as function parameters: fun1[x_]:=x^2 Is there any point to using a variable in a function definition: ...
1answer
46 views

Extract part of list by reading it in a cyclic manner

I have trouble extracting part of a list in a specific order, say, increasingly in a cyclic manner. For example, I have the following list list={0,10,6,-5,-10} ...
1answer
57 views

How to complete boundary in masked image?

I am trying to generate a mask of the elliptical boundaries in this object. Any ideas on how I could complete the edge of a partially filled elliptical object? Thus far, I've obtained a mask that is ...
0answers
40 views

How do I insert Unicode into a MySQL database?

I'm having trouble transferring Unicode strings from one MySQL database to another using DatabaseLink functions. Here is my failed attempt to read a string from ...
2answers
63 views

Interpolation of a vector [closed]

How can we use a sample data for interpolation of a function within a domain. But I need all interpolated values at once in a vector format. For instance, below I create a range of values for ...
0answers
23 views

ParallelDo issue with SQLExecute (SQLite) [closed]

This code run as expected if I use Do[...], but if I use instead ParallelDo[...], as in the code bellow, the SQL INSERT statements seems to be completely ignored. In both cases, the filename is ...
1answer
63 views

NonlinearModelFit memory problem

I have a problem while trying to make a nonlinear fit of the following data: qn = NSolve[Tan[q] == 3*q/(3 + 1870715*q^2) && 0 < q <= 65, q] ...
0answers
18 views

How to plot eigenvalues as a function of parameters in a dynamic module?

I am trying to make a fancy interactive plot that shows how the eigenvalues of a matrix mat change under variation of parameters ...
2answers
71 views

FindInstance is very slow on an apparently simple problem

I wish to use FindInstance to find a set of solutions of this problem: ...
1answer
61 views

Plot option Filling conflicts with option PlotLabels

The regulars here discuss approaches to numerically unstable systems of higher-order PDEs, and I cannot even paint by numbers … (sigh) A Plot[] of simple curves with ...
1answer
230 views

How to make datasets display correctly?

NB: The problem illustrated below is truly ubiquitous. I hope the examples given below are sufficiently different to demonstrate this fact, and to discourage answers that hinge on the details of the ...
2answers
161 views

Save as PDF without cell numbers

I want to save a notebook file as PDF, but without cell numbers. For instance, take this document, then select “save as PDF” and the result is, How can I remove the cell numbers ...
0answers
43 views

Grid of plots - alignment [duplicate]

I'm trying to plot several plots and graphics into Grid, but I have no success with proper alignment. Here is my code: ...
0answers
42 views

How can I plot 2 concentric fixed circles with a polygon inscribed in one and circumscribed about the 2nd

Can anyone help me with the simplicit code to plot 2 concentric circles and a polygon of sides n (that I can manipulate) inscribed in one circle and circumscribed about the other. However I want the ...
0answers
59 views

Find and Replace in Notebook using a Pattern [closed]

I would love to be able to use the power of Mathematica's patterns to find and replace within my code. I have searched for this on google, and so far I've come up with this: ...
0answers
33 views

How to Select the elements of a list so that GCD equal to 1

I have a list ...
2answers
106 views

Function does not execute commands and fails to evaluate [closed]

The code I am trying to execute: hh[x_, y_] := x + y; hh[{3, 4}] The expected output: 7 However, on output I get ...
1answer
1k views

How does a Pringle lose its curvature?

Nom! As part of a bigger project, I've was writing some code to calculate the scalar curvature of surfaces of the form $z = f(x,y)$. This uses a general calculation of the scalar curvature to produce ...
1answer
42 views

How to set MaxStepSize for spatial variable in NDSolve?

When applying NDSolve to a 1-D transient heat equation, the following code appears to set MaxStepSize for the temporal variable t. ...
0answers
44 views

How to make sure that Mathematica doesn't hog memory for intermediate steps while using functions like FindRoot? [closed]

I am using Mathematica 10.4. I am trying to solve a set of around 10000 non-linear algebraic equations that I have computed upon discretization of a set of coupled non-linear differential equations. ...
1answer
65 views

Why does Position` by default return a list of lists of positions instead of a simple list of positions?

Position[{1,2,3,4,2,3,4,5},2] (* Output: {{2},{5}} *) Why does Position work this way? I understand this form might be ...
0answers
38 views

Flatten works in output but not in Global Workspace?

I am trying Michael Trott's Sierpinski Triangle. ...
0answers
38 views

How to remove a bar that blocks some upper space that says “WOLFRAM STUDENT EDITION” so forth? [duplicate]

There is a bar field on the upper screen of Mathematica that occupies some space, that says "Wolfram Mathematica : STUDENT EDITION" so forth. I would like to utilize the field instead of letting it ...
2answers
87 views

How to reduce each column of a dataset?

Given a simple dataset like this one: ...I want to apply some reduction function (like Total or MinMax) to each column ...
0answers
32 views

the graphic doesn't appear

The data is in this link: https://www.dropbox.com/s/vlvcwdszsiglce9/texto.txt?dl=0 ...
0answers
44 views

High Precision Plots of Eisenstein Series [closed]

When plotting the Eisenstein Series (great information here Eisenstein Series in Mathematica?) you observe highly non-trivial branch cut behavior close to the real axis. This makes the numerics break ...
1answer
53 views

Why is head evaluation inconsistent in pattern replacement?

I noticed the following unexpected result: In[90]:= "foo" /. x_String -> Head[x] Out[90]= Symbol Why is it that Head[x] ...
1answer
49 views

Errors only when code is iterated

Hello I'm trying to have two for loops sweep two parameters and for each 2-tuple of those parameters I want to solve a differential equation. To do this I have the following code: ...
3answers
92 views

Find extremal values while plotting

I have a parametric function {x[t],y[t]}. I then do ...
1answer
82 views

Tedious integral

I'm new to Mathematica so I'm not familiar with its potential use to solve tedious symbolically integrals. I'm trying to solve the following one: ...
1answer
39 views

An error comes up while exchanging stylesheets

A notebook contains ...
2answers
326 views

Draw a circle through 4 points on parabola [closed]

I have two dynamic perpendicular parabolas: $y=ax^2+c, x=by^2+d$, which intersect in four points (the coefficients are chosen that way). There is a fact that we can construct a circle through these ...
0answers
39 views

3D Plots and vector fields [duplicate]

I'm a beginner. How I make a 3D Plot from zero? (like a graphics with the potencial of the electric field). I have to make vector fields too. (vectors of the electric field). I search at internet but ...
0answers
17 views

find minimum spanning tree,but not define starting and ending vertice?

find minimum spanning tree,but not define starting and ending vertice..
0answers
33 views

From “NMinimize::nosat: Obtained solution does not satisfy the following constraints within Tolerance”, can prove something?

I got a very very complicated function G[r1,r2,F1,F2] to minimize. It has four variables, r1,r2,F1,F2. When I introduce the ...
0answers
19 views

General question about solving a large set of linear equations efficiently

In my research, I got a large set of linear equations, about 10 000 equations with more than 10 000 variables. It is not efficient to use "Solve", so does anyone know any way to solve the equations in ...
2answers
132 views

Running Mathematica Notebook files in command mode

The question is, how can I run a .nb file in the kernel mode of Mathematica? I am not an expert in Mathematica, but one of our users who use this program says that ...
0answers
33 views

GeoRegionValuePlot does not show Legends

I have a problem with GeoRegionValuePlot. These are the settings: ...
1answer
73 views

Given Latitude, Longitude, and Elevation, how to illustrate a three-dimensional path?

I've extracted detailed path information from a .FIT file and would like to plot this in three dimensions. I assumed GeoPositionXYZ[] would be useful, and have translated the data into a list that ...

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