3
votes
1answer
501 views

Why the complicated pattern in this 3D plot?

ListPointPlot3D[ Table[{n, s, (Prime[n]^s/(Prime[n]^s - 1))}, {n, 1, 2000}, {s, 2, 80}], PlotRange -> All] Is the pattern the result of the data, the ...
0
votes
1answer
110 views

Define a function that takes ragged array [closed]

newbie here. I want to define a function that takes a ragged array and return another one, but how. Say, I want to define a simple function behaves like this ...
0
votes
0answers
60 views

How to compute variances from a matrix/table

I have created a matrix/table with an imported dataset. I want to know what the variance is for 3 values at a time but across 68 columns. I would like to do this in an automated way rather than 1 set ...
2
votes
1answer
180 views

Aligning controls and their labels to grid?

I have a Manipulate with 6 sliders controlling 6 different variables. I have labelled them all. The problem is that the labels have different lengths, so it looks a ...
7
votes
1answer
150 views

Explain the difference between ViewPoint and ViewVector?

I've read the documentation, but am still very unclear as to what the difference is between ViewVector and ViewPoint for ...
1
vote
0answers
78 views

Linear interpolation over 2 variables

I'm tuning a function to data over 4-5 variables using Differential Evolution. The objective function calls frequently interpolation function. I came to a point, where compiling the objective function ...
25
votes
1answer
613 views

Undocumented form for Extract

Prompted by a comments conversation here, here's an interesting (and often performance enhancing) use of Extract: ...
0
votes
3answers
98 views

Removing a ProgessIndicator when no longer needed

I have a progress indicator in my Mathematica notebook that I update as various calculations are performed: indicator = ProgressIndicator[Dynamic[progress]]; I ...
0
votes
0answers
263 views

A problem with functions and Infinite expression 1/0 encountering

Following code (function) makes integrals and then replace f[x] with Cos functions and calculate the definite parametric ...
0
votes
1answer
122 views

A problem with set values

The following code is just an example to clearly explain my problem. Assume that : ...
4
votes
0answers
119 views

How to get mathematica to simplify a result

I have the following output $\text{Li}_2\left(3-2 \sqrt{2}\right)-4 \text{Li}_2\left(-1+\sqrt{2}\right)$. This turns out to be equivalent to $\displaystyle\log^2(1+\sqrt{2})-\frac{\pi^2}{4}$. How ...
2
votes
1answer
221 views

Another one problem with legends on GraphicsGrid

I have used ListLinePlot to generate this grid of plots: and I want to add a legend in Row Layout below this grid. My code, has as follows: ...
1
vote
0answers
107 views

An example of how to compute numerically the KL-divergence in mathematica [closed]

I wanted to compute an exact number for two probabilities that I am comparing. These are two normal distributions as: $$Normal(\mu = 5, \sigma = 4)$$ $$Normal(\mu = 5, \sigma = 5)$$ I decided to ...
2
votes
1answer
169 views

What are these strange shapes in my Plot3D[]? [closed]

Plotting a function, I noticed some strange spots away from the main feature, the dark purple here: You can see that they don't actually have any curvature themselves: Strangely, you don't see ...
1
vote
2answers
148 views

Making mathematica do regulated integrals

Consider the integration, $\int _0 ^\infty dx\ x \tanh( \pi x) \sqrt {x^2 + a^2 } $ where $a$ is a real number. This integral is divergent. We note that an asymptotic expansion of the integrand ...
0
votes
0answers
173 views

Making single letters non-italic in Graphics/Text/Style objects

Suppose that I use Graphics, Text, and Style to type one letter in the subscript of a letter ...
16
votes
2answers
1k views

Scan vs. Map vs. Apply

I cannot understand the difference between Apply, Scan, and Map. I have tried to play with ...
0
votes
1answer
33 views

How would I enable the Evaluate in place item of the Evaluate menu?

I would like to be able to suppress multiple outputs when a cell is evaluated. Is there a way to enable the "Evaluate in place" menu item of the Evaluate menu?
0
votes
1answer
106 views

Create new file, based on 500 articles

I've got a folder with 500 newspaper articles. Each article is saved in a seperate file with a number in the title like "1.txt", "2.txt". Each article has a date but it is not clear in which line the ...
6
votes
3answers
286 views

Map structure of irregular list, Flatten then reconstruct list using structure

I'm trying to use Compile[] to improve the performance of an algorithm. The algorithm works on a set of matrices which are not of a similar shape. Unfortunately ...
2
votes
3answers
208 views

Recover data points from RGBColor of known ColorScheme

In general I want to recover the z-values from an image of a DensityPlot. A simple example might just be ...
2
votes
0answers
47 views

$Failed below input area of new cell in notebook

The Mathematica 9 installation on my laptop has developed an odd feature. Just underneath the grey line indicating the input area for a new cell, the expression ...
0
votes
1answer
72 views

Sorting a table of vectors with weights [duplicate]

I'm trying to simplify a table, for instance {{1, {4, 2, 0}}, {4, {2, 4, 0}}, {-2, {3, 3, 0}}, {1, {3, 0, 3}}, {-3, {0, 4, 2}}} Here the first column is the ...
3
votes
2answers
158 views

Mathematica not recognising closed forms as specific values

I have a Mathematica program that outputs a piecewise function, and some parts of the expression are not being recognised as specific numbers when using ...
0
votes
1answer
65 views

Dsolve is not solving equation ( 3 system with 2.order diferantial equations) [closed]

I added an image of my equations at the bottom. I dont understand why it is not solving. This is 3 systems with 2.order diferantial equations. I also put my initial conditions. But it is not solving. ...
1
vote
1answer
313 views

Why my differential equations become True? [duplicate]

I've been trying to solve a system of nonlinear differential equation, but the conditions are a bit weird. Two of the differentials equate to the same equation, but have different boundary ...
1
vote
1answer
259 views

Get Cos[2 x] in “Solve”

My goal is to get an analytical solution of x ( $\lambda$ in the problem), when $\epsilon$ (f[x] in the problem) is maximum (use inverse form). I found that if I can use trigonometric identity ...
0
votes
0answers
62 views

Derive a PDE from other PDEs

I'm trying to do some symbolic calculation like this: Substitute (11.2) into the last two of equations (11.1) and, in turn, substitute these into the first of equations(11.1), I want to ...
4
votes
1answer
138 views

Shift text upwards in graphics so characters with descenders clear horizontal lines

Is there an option to align Text to automatically adjust for font descent? In the attached graphic, strings that contain "g" are visibly shifted upward, even though all strings are uniformly ...
2
votes
0answers
112 views

Displaying primes as a 3D array of spheres

I am currently learning my way through Mathematica and have stumbled upon a strange problem. It is asking me to implement PrimeQ into ...
0
votes
0answers
52 views

problem solving a simple integral equation

I'm looking for a function q(x) so that integral( q(t) , t , x, x+2*pi/3) == a*sin(x)+b Could anyone help me on this one? Thx in advance
1
vote
0answers
119 views

How can I make my MM code more compact and readable? Can I put functions in different notebooks?

I'm doing some coding in MM9, but my program is getting quite large. It's mostly a bunch of functions defined at the beginning of it, but it's getting to the point where I have to scroll for a few ...
0
votes
0answers
112 views

How can I use a For loop in a recursive function?

I am creating a simple radix2 FFT algorithm (based on Cooley-Turkey) by using a recursive function to obtain the fft. The function is supposed to work on a list (assuming the length is a power of ...
1
vote
1answer
88 views

Limit as n -> ∞ for RSolve with Multivariate Recurrence Relation

I'm trying to solve the following when n -> ∞: ...
2
votes
2answers
136 views

Automatically highlight certain cells

I am looking for a method to highlight certain cells in a table/Grid based on meeting some user defined conditions. As an example: ...
0
votes
1answer
153 views

How to efficiently distinguish the rewired edges in WattsStrogatzGraphDistribution?

The WattsStrogatzGraphDistribution function is a way to construct random graphs based on Watts and Strogatz small world model. The ...
1
vote
2answers
70 views

Unintentional function memoisation via Dynamic

I needed to display edge labels of a graph in a way that allows the edge labels to be moved. ...
0
votes
1answer
133 views

Easy NMinimize does not converge

I try to minimize the following for a>0: f[a_] := Gamma[3]*a^(-3)*(Integrate[Exp[-u]*(u - a)*1/u, {u, a, Infinity}])^(-1) I put in ...
0
votes
0answers
68 views

How to save all data in all variables in context different than “global”?

I have seen questions on saving data on "global" context. Now if I set my notebook's evaluation context "unique to this notebook". the global context doesn't work quite well. Any idea what should i do ...
1
vote
3answers
127 views

Initialize table in a Module but Break if criteria not met

I am initializing a table inside a function as follows: f[a1_, a2_, a3_] := Module[{RM = Table[a1+a2+a3+i1, {i1, 1, 10}]}, Plus@@RM] I am calling the function ...
1
vote
0answers
71 views

Summing a trig series

I am trying to sum the following expression: (Cos[(2 π m)/N]^2 Cos[(2 π n)/ N])/(2 (Cos[(2 m π)/N] - Cos[(2 n π)/N])) from ...
1
vote
1answer
46 views

expression contained across multiple cells

Is it possible to span one expression across multiple cells? E.g. long if statement or function evaluation. I looked in documentation and searched forum/google and could not find.
6
votes
1answer
312 views

Resume/continue interrupted evaluation

I interrupted an evaluation to quickly do something else. How do I resume the interrupted evaluation? I cannot open the "Interrupt evaluation" window, as it is disabled. There is no "Resume" button to ...
3
votes
5answers
453 views

Randomly selecting and reinserting a subset of elements in a list

This question is similar to my other question: How do I randomly select 'k' positions in a list and shuffle their respective elements without effecting the other elements? Imagine first a ...
2
votes
1answer
98 views

How do I constrain movement for lists of Locators using 2nd argument of Dynamic?

I need to display edge labels of a graph in a way that allows the edge labels to be moved. Locator seems the simplest and most obvious function to use. My ...
0
votes
1answer
95 views

Open a pre-existing CDF file from a stand-alone CDF file

This is related to my previous question here A series of my questions are related to an important problem: It is important to be able to CDF-publish a document, and be able to open a separate ...
0
votes
1answer
103 views

Equation in implicit form

This is simple example: v = {1.48622576, 1.53444276, 1.42299438} v/(v + 1) Out[1]:= {0.597784, 0.605436, 0.587288} In the above case expression v/(v + 1) is ...
1
vote
1answer
45 views

How to set the values into some variables from different lists [closed]

I have a list of Values and a list of variables. I want to set the Values into Variables. Assume the following code: ...
1
vote
0answers
54 views

Mathematica program for PLUR decomposition of a symbolic matrix using full pivoting

I wanted to ask if there is a Mathematica program for PLUR decomposition of a symbolic matrix M, such that M = P*L*U*R, using FULL (row and column) pivoting, and where R = reduced row echelon form of ...
4
votes
1answer
175 views

How do I randomly select 'k' positions in a list and shuffle their respective elements without effecting the other elements?

Imagine I have some list: listA = {"a","b","c","d","e","f","g","h","i","j"}; I'd like to randomly select k positions in the ...

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