4
votes
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 ...
0
votes
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 ...
3
votes
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 ...
10
votes
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 ...
4
votes
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 ...
2
votes
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 ...
6
votes
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}|>}]; ...
0
votes
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 ...
0
votes
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 ...
0
votes
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 ...
1
vote
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 ...
1
vote
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: ...
2
votes
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} ...
1
vote
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 ...
3
votes
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 ...
0
votes
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 ...
2
votes
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 ...
1
vote
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] ...
0
votes
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 ...
0
votes
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: ...
4
votes
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 ...
10
votes
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 ...
2
votes
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 ...
1
vote
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: ...
0
votes
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 ...
2
votes
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: ...
0
votes
0answers
33 views
1
vote
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 ...
10
votes
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 ...
1
vote
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. ...
0
votes
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. ...
2
votes
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 ...
1
vote
0answers
38 views

Flatten works in output but not in Global Workspace?

I am trying Michael Trott's Sierpinski Triangle. ...
0
votes
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 ...
2
votes
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 ...
-1
votes
0answers
32 views

the graphic doesn't appear

The data is in this link: https://www.dropbox.com/s/vlvcwdszsiglce9/texto.txt?dl=0 ...
1
vote
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 ...
2
votes
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] ...
0
votes
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: ...
2
votes
3answers
92 views

Find extremal values while plotting

I have a parametric function {x[t],y[t]}. I then do ...
0
votes
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: ...
0
votes
1answer
39 views
2
votes
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 ...
0
votes
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 ...
-1
votes
0answers
17 views
0
votes
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 ...
0
votes
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 ...
4
votes
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 ...
3
votes
0answers
33 views

GeoRegionValuePlot does not show Legends

I have a problem with GeoRegionValuePlot. These are the settings: ...
2
votes
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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