1
vote
1answer
272 views

How to reject or repulse some points in a 3D cloud of particles?

I'm having an issue with a 3D distribution of points. The distribution is really nicely looking in Mathematica, but it is used in an OpenGL astronomy program (Celestia) to generate a nebula, with ...
4
votes
1answer
128 views

Identical code, different answers?

I'm having some trouble with identical code giving different answers. On a fresh kernel (MM 9.0.0.0, Windows 64-bit), running the same code, copy-paste, gives two different answers: ...
1
vote
2answers
456 views
4
votes
1answer
194 views

Remove the white margins of a Graphics3D figure

If the option Boxed is set to be False in Graphics3D, additional white margins may appear as ...
0
votes
1answer
178 views

Why won't ContourPlot accept a variable argument? [duplicate]

I have a list of linear inequalities which describe a (polygonal) region. I can use RegionPlot to visualize this region; but I'd also like to overlay this plot with ...
5
votes
2answers
234 views

Keep Ordering of Bra Ket When Printing

I would like to keep the ordering of the bra ket-print but right now this doesn't happen. Any Idea? I tried playing with HoldForm but then i could evaluate the expression inside properly ...
2
votes
1answer
157 views

EmpiricalDistribution for Gini Coefficient Runs Slow

I am repurposing code that I found in this blog post (http://datavoreconsulting.com/sports/gini-coefficients-and-the-olympic-medal-race/) to generate the Gini coefficient for other data sets I am ...
5
votes
3answers
284 views

Integration gives ComplexInfinity when it shouldn't

A simple example of my problem is that Assuming[k ∈ Reals, Integrate[Exp[l]/((1 + Exp[l])*Exp[k*l]), l]] /. {k -> 2} gives ...
6
votes
2answers
278 views

Find all permutations with a condition

How can I find all the permutations of {a, b, c} where a + b + c = n? For instance: if ...
6
votes
6answers
849 views

How to simplify a complicated Sum in terms of power Sums?

For example, I have: $a=\sum _{r=1}^n x_r \left(\left(\sum _{i=1}^n x_i-x_r\right){}^2-\sum _{i=1}^n x_i^2\right)$ ...
0
votes
2answers
297 views

Cumulative frequency plot

I have the following data: data = {{0, 0}, {20, 1.4}, {25, 9.8}, {30, 32.2}, {35, 38.2}, {40, 15.6}, {45, 2.7}, {50, 0.1}}; where the second coordinates are ...
3
votes
1answer
171 views

How to show error messages in current notebook?

I would like Mathematica to print error messages in current notebook together with output. This is default option in Mathematica, but recently I turned it off somehow. Now, I am getting output in ...
2
votes
1answer
57 views

Avoiding re-evaluation of RegionPlot3D on a second computer

After running a RegionPlot3D named "testplot" on my desktop, I followed an earlier suggestion from the forum and saved it using: ...
2
votes
1answer
220 views

Interpolation on large 2D list results in erratic function

Previously, I've had problems with Mathematica interpolating and plotting 3D lists, but I finally managed to do so by rescaling the x and y-axes with the help of the methods proposed here. Now my ...
4
votes
3answers
366 views

Using Manipulate to vary the frequency of a sound produced by SoundNote[]

I have tried various ways to combine Manipulate and Sound/SoundNote that would allow me to vary the frequency of a sound while it is being produced. The addition of Dynamic didn't help, but did ...
4
votes
1answer
169 views

Plot3D list elements

I've been having some trouble with Plot3D. I have a quite complex function of two variables (actually three but the first one doesn't matter) that returns a list ...
-4
votes
1answer
105 views

Exporting data from different notebooks to a common file

I am doing some calculations from different notebooks. I need to export the results from all those notebooks in columns of the same file, like a1 b1 c1 a2 b2 c2 a3 b3 c3 . . . where a, b ...
1
vote
2answers
293 views

Select rows from table by keys

I am looking for a way to iteratively select all sublists with the same ID (my 1st column, residual columns are AbsoluteTime entries). First, I obtained the list of ...
4
votes
2answers
460 views

Transparent Cylinder with Dashed Edges only

I would like to have that kind of cylinder with Dashed edges (including the bellow inner ring): I've been trying that: ...
0
votes
1answer
164 views

Interpolating a Bivariate Polynomial over a Finite Field

Let $F=GF(p)$ be a finite field, $p$ prime and write $F^\times=\{x_1,\ldots,x_n\}$. I'm trying to implement an earlier version of Sudan's list-decoding algorithm for Reed Solomon Codes ...
8
votes
3answers
268 views

Reduce the output from tuples by including symmetry?

I need all the possible 3x3 binary tensors, but I'd like to have this account for symmetries. I've started by using the Tuples command. Tuples[{1, 0}, {3, 3}] ...
2
votes
1answer
102 views

Cell background color changes cell layout

When I change the background color of a cell like in the colored cells become slightly indented and their line spacing is increased. How can I change the cell background color while keeping the ...
8
votes
2answers
513 views

OpenSCAD like functionality with Mathematica?

I keep seeing reference to use of Mathematica as a CAD tool (for instance: http://www.makerbot.com/support/guides/design/). I'd like to use it as such if feasible, but I'm having trouble locating ...
3
votes
3answers
377 views

Horrific Looking Contour Integral in Mathematica Plot:

I'm attempting to display the geometric meaning of a contour integral but as you can see, the typesetting of the contour integral (created via the Epilog function) looks awful because the contour ...
0
votes
2answers
193 views

How to format problem in WolframAlpha? [closed]

Is there a way to enter this problem in WolframAlpha?: the sum of the reciprocals of two consecutive integers is -9/20. Find the two integers.
10
votes
3answers
667 views

Why doesn't my script work when I redirect stdout?

I'm using Mathematica Home Edition 9.0.1 on Mac OS X 10.8.2. I have this script: ...
6
votes
1answer
237 views

Launching remote slave kernels on HPC causes slow down

I had a post earlier regarding how I can run Mathematica at a HPC cluster (running PBSpro) by having a single MathKernel launch ...
9
votes
3answers
663 views

Dashed mesh behind 3D object

I am trying to create a simple, almost transparent 3D sphere with a mesh that is made of solid lines if they are on the front surface (i.e. if they are directly visible) and of dashed lines if those ...
2
votes
1answer
131 views

Avoiding the re-evaluation of a RegionPlot3D

Is there a simple way to save the output from RegionPlot3D so as to avoid re-evaluating when the notebook is re-opened and Show ...
1
vote
0answers
48 views

Definition of differential operators [duplicate]

I am curious how differential operators are defined in Mathematica. More specifically, if the Laplacian function wasn't available, how would one go on to define such a function in Mathematica directly ...
5
votes
0answers
172 views

Convert logical relational expression to / from disjunctive and conjunctive forms?

I would like to convert logical relational expressions in disjunctive form, e.g., $$(x \lt -1) \lor (-1 \lt x \lt +1) \lor (x \gt +1)$$ into conjunctive form, e.g., $$(x \ne -1) \land (x \ne +1)$$ ...
1
vote
1answer
199 views

Finding rational roots to an equation (univariate) [closed]

So I'm using Mathematica 7 for Students and I'm using the Root function to find the roots of an equation over the rational numbers: $$225x^6 -343 = 0$$ I created ...
1
vote
1answer
154 views

Solving a system consisting of an ODE and a non-differential equation

I would like to solve the following system of equations: y'[t] == x[t]*y[t] - x[t]; 10 == x[t]*y[t]/(x[t] + y[t]) + x[t]/(x[t] + y[t]^2) Is there any way to ...
4
votes
1answer
327 views

RefProp in Mathematica

RefProp by NIST is a program that calculates the thermodynamic properties of fluids. I need to call certain RefProp functions ...
4
votes
3answers
549 views

Graphical Plots of PDF and CDF

I have a joint density and distribution function that I want to plot in a meaningful way, (i.e., want to be able to see how the functions behaves as changes in x and y happen simultaneously. If ...
6
votes
1answer
1k views

Spiral pattern and Fibonacci numbers

I'm want to generate a 2D spiral pattern like the the one shown in the following figure. I can generate the spirals one by one, but I think there ought to be a more efficient method for generating ...
21
votes
3answers
344 views

Efficiently appending points to a NearestFunction

I have a program which works with a list of points (in 3D, but it could be in 1D as well, it won't make a difference). Within a loop, it keeps adding new points to the list. To calculate the ...
5
votes
2answers
3k views

Solving a tridiagonal system of linear equations using the Thomas algorithm

I'm trying to write a function that can solve a tridiagonal system of linear equations using the Thomas algorithm. It basically solves the following equation. (Details can be found at the Wiki page ...
4
votes
0answers
137 views

Version 8.0 integrates but Version 9.0.1 doesn't

I am trying to run the following integral in version 9.0, but it fails: ...
4
votes
1answer
201 views

Manipulating a Graphics3D output with a large number of geometric primitives

I'm attempting to view and rotate a Graphics3D object with a very large set of geometric primitives ($\approx 10^6$ objects such as spheres or lines), and everything is functioning very slowly. Are ...
10
votes
4answers
714 views

How to draw a higher-genus surface

NB: By higher-genus surface, I mean a closed orientable surface of genus at least 2. This question has come up before on math.SE, and even MathOverflow, but most posters suggested using either ...
4
votes
1answer
99 views

How can PixelConstrained be emulated with DensityHistogram?

This DensityHistogram doesn't display very well. Some bins are shown much larger than others and, oddly, empty bins appear to be drawn smaller than occupied bins. ...
5
votes
2answers
866 views

Exporting a .xlsx file with about 500 columns

When I want to Export["text.xlsx", data] where data is a matrix with 500 columns and 10000 rows, I get the error message: ...
0
votes
0answers
70 views

How to define the tangent gradient operator? [duplicate]

I would like to define a new differential operator that is the tangent gradient for a curve $\Sigma$. This is defined as $$\nabla_\Sigma=\mathbf{P}\nabla$$ where $\mathbf{P}$ is the projection ...
2
votes
0answers
77 views

SetDelayed and avoiding function calls through memoization [duplicate]

I am fairly new to Mathematica. I am working my way through a number of books. I have been looking at the use of SetDelayed and want to confirm that my ...
2
votes
0answers
152 views

Problem when merging cells including commentary

This is a more of a problem report than a question. When merging the two cells Cell1: foo (*foobar*) bar and Cell2: ...
3
votes
2answers
470 views

How to change default settings of cell formatting?

I find font size of Text cells too small and I like displaying them with background colour... I've read this question and learned about ...
2
votes
0answers
176 views

Solving $k\log(n) - k\log(k) \leq u$

How can I persuade Mathematica to help me find solutions to the inequality $k\ln(n) - k\ln(k) \leq u$ over the reals, assuming $u \geq n \geq k \geq 1$. When I evaluate ...
6
votes
1answer
150 views

Go to definition of symbol/variable

Is there any easy way of directly jumping to the definition of a Variable like it is implemented in some good IDEs? Currently I have to search manually (ctrl+f) through the whole workbook to find it ...

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