0
votes
0answers
70 views

complicated Numerical Integration, FEM application

I am trying to calculate a 2d Integral which has another 2d integral in the integrands. here is the setup: ...
0
votes
0answers
72 views

Mathematica function Det has unexpected behavior

I am using Mathematica "Kernel" -> {"Version" -> "9.0 for Microsoft Windows (64-bit) (January 25, 2013)", "ReleaseID" -> "9.0.1.0 (4055652, 4055188)" on a Win 7 machine. The file listed below uses ...
1
vote
1answer
78 views

Generate a list of values with equal number of each value

I want to create a list of 32 values such that from {a,b} I can generate ...
0
votes
1answer
64 views

Can ParallelDo speed up a counting problem?

How to make parallelize the following code keeping the same "idea". The example I have in mind is more complicated, but I would like to know if a program of this structure can be parallelized? ...
0
votes
0answers
21 views

Optimizing FindInstance for large systems of Diophantine equations [closed]

I have a system of Diophantine equations, with about 15 equations and 25 unknowns. To find at least one solution to this system I can use FindInstance and specify the domain to be Integers. But in ...
0
votes
1answer
60 views

looping in mathematica for using the current value as initial state of next value [closed]

i have some initial state $psi[x,t]$. I perform some operation on it and store the value in another state $pi1[x,t]$. Now on the next step i have to use $psi1[x,t]$ as initial state and perform the ...
6
votes
0answers
71 views

HighlightGraph and Hyperlink

In the documentation of Mathematica it is mentioned that you can use Hyperlink and Tooltip as wrapper in a similar manner as ...
2
votes
2answers
132 views

region plot in a 2-simplex

I want to plot a 2-dimensional region with constraint $x+y\le N$, i.e., I want to plot a sub-region inside a 2-simplex. As an example: ...
4
votes
1answer
68 views

What string pattern will match $n$ contiguous characters drawn from a given alphabet?

I'd like to use StringCount to count the number of subwords in a string that have the form **** where ...
0
votes
0answers
21 views

How do I plus these values in a list [duplicate]

Hi I need to plus 3 values together each time for the rest of the list. How do I basically add the 3 sets of values together each time. When I try Plus[] it returns the same input values back to me ...
0
votes
1answer
76 views

How to get more accurate orthonormal eigenvectors?

I have a matrix M with real entries in MachinePrecision. I compute its eigenvectors and construct matrix ...
0
votes
1answer
42 views

Pattern matching with PDF, Distributed and multivariate distributions

I have defined a function to compute the Shannon entropy of a probability distribution: ent[p_] := Expectation[-Log[PDF[p, x]], x \[Distributed] p] This works ...
1
vote
1answer
59 views

How do I use Subgraph to sample the $n$ vertices of a graph with the greatest connectivity?

Let $G$ be an arbitrary graph with some number of vertices $||V||$ and some number of edges $||E||$. We can use Subgraph to generate, well, a subgraph of ...
3
votes
1answer
466 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
0answers
49 views

Solving Laplace-Beltrami Equation on a Curved Surface [closed]

Suppose that we have a curved surface $S$, specifically, $S$ is a bump, i.e., $x=\rho\cos(\theta)$, $y=\rho\sin(\theta)$, $z=h\cos^2(\frac{\pi\rho}{2R})$, where $\rho$ runs from $-R$ to $R$ and ...
0
votes
1answer
70 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
51 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 ...
0
votes
0answers
32 views

Splitting a list into list of lists [closed]

I am trying to split a flattened list of data into a list containing 4-vectors. Consider the sample set of data (number of elements always a multiple of 4) ...
2
votes
1answer
55 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
77 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
36 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 ...
19
votes
3answers
359 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
76 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
37 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
75 views

A problem with set values

The following code is just an example to clearly explain my problem. Assume that : ...
3
votes
0answers
73 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 ...
0
votes
0answers
40 views

draw graphics in cycle [closed]

Good evening. I've made the following plot g1 := Plot[f[x], {x, -3, 5}] gr1[f_, xmin_, xmax_, slices_] := Module[{span = (xmax - xmin)/slices, ext}, ext[op_, r_] := First@Quiet@op[{f[x], r ...
1
vote
1answer
65 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
31 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 ...
1
vote
1answer
132 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
votes
0answers
47 views

Solving nonlinear system by newton method [closed]

How to solve nonlinear system by newton method (without Findroot method)? What is algorithm?
1
vote
2answers
127 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
27 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 ...
7
votes
2answers
211 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
23 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?
-1
votes
0answers
42 views

solving simple integral equation [closed]

Could someone help me finding q(t) so that \begin{equation} \int_x^{x+2\pi/3}q(t)\,\mathrm{d}t = a\cdot\sin{(x)}+b \end{equation} Thanks in advance!
0
votes
0answers
13 views

how to find find a matrix by the characteristic vlaues and vectors [migrated]

Now I am studying linear algebra course, In that for a given matrix we are finding the characteristic values (eigen values) and characteristic vectors (eigen vectors). But my question is why cant we ...
0
votes
1answer
84 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 ...
0
votes
0answers
18 views

Is it possible to suppress additive outputs when cells are evaluated? [closed]

Is it possible to suppress multiple outputs when a notebook is evaluated? Ideally, I would like to have a notebook with single instances of output. Currently when I open a notebook, I have to ...
6
votes
3answers
205 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
113 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
37 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
48 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
119 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
45 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. ...
0
votes
1answer
70 views

Solving System of Nonlinear with Three Differential Equations

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
97 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
49 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
90 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
80 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 ...

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