0
votes
0answers
53 views

Automatic method for NDSolve [duplicate]

How can I understand which method Mathematica automatically chooses to use for numerically solving the following two equations? 1: ...
0
votes
0answers
182 views

Calculating the Lyapunov Exponent/Spectrum for the Duffing Oscillator

Some fellow students and I are trying to calculate and plot the Lyapunov spectrum for the Duffing oscillator (currently a test approach). Each of us has Mathematica knowledge based purely on past ...
6
votes
1answer
231 views

If doesn't compile if its output is the output of Compile?

The smallest sample I can find to reproduce this problem is: test = Compile[{}, If[True, 1]]; << CompiledFunctionTools` CompilePrint@test ...
9
votes
2answers
333 views

Measuring curve length on a binarized image

With the help of almighty Mathematica 9, I got from this To this: with this code: ...
0
votes
0answers
44 views

Export Messing Up Alignment of Bar Chart

Here is my code: ...
5
votes
4answers
186 views

ContourPlot refuses to show in-figure PlotLegends after turn on ContourShading

I would like to do a contour plot with a label inside the figure. For example, the following works well. Note there is a small "example" at the right bottom figure. ...
0
votes
0answers
44 views

How to get integer/rational and real eigenvectors to be the same? [duplicate]

forgive me if I missed this already being answered or too easy. Given a matrix: q = {{1, 3, 5}, {7, 11, 13}, {1/3, 1/7, 1/13}}; Eigenvectors are different here: ...
8
votes
4answers
864 views

Filling a curve between a line and the x-axis

I'm trying to plot the function $f(x)=\dfrac{1}{x^2}$, filling the square area from (0,0) to (1,1) with purple and filling the area under the curve from 1 to 4 with red. However, Mathematica is not ...
4
votes
2answers
84 views

How can I make a stylesheet where inline cells have are styled like input cells?

How can I make a stylesheet where inline cells have are styled like input cells? By "similar", I mean the same font and syntax highlighting. I have even tried copying all settings from ...
1
vote
2answers
119 views

Few quick Mathematica questions about Dictionary

a. Get the list whose elements are of the form {language,number of words in dictionary) I tried this, and it gave me the number if words in dictionary, but I don't know how to get the language part: ...
7
votes
1answer
361 views

Using KalmanFilter or KalmanEstimator

I have the following: ...
0
votes
1answer
49 views

Help with Reduce, quadratic system of inequalities

I'm trying to obtain an equivalent system of inequalities to the one below but without the variables x and z. Somehow Reduce just repeats the command. ...
0
votes
2answers
120 views

SplicedDistribution - different definition across Mathematica 9?

I am having troubles with my notebook. I succesfully defined Asymmetric Laplace Distribution at school using SplicedDistribution function, and Mathematica was able ...
1
vote
1answer
138 views

How to specify the centre or PlotRange of a Graphics3D?

When I create a Graphics3D, I often want to place an object right at the centre of the box. Initially I thought that the centre was specified by ...
11
votes
1answer
262 views

Bizarre behavior of With, Compile and Break

I'm guessing this is almost certainly a bug in Compile (because they're fairly common), but it's pretty weird and I spent about an hour tracking down the issue and ...
0
votes
4answers
152 views

RSolve fails on a two-equation non-linear system

I have a system of just two recurrence equations, I need to solve them and so I use RSolve: ...
3
votes
1answer
154 views

Determining the dimension of a probability distribution

Functions like Mean and RandomVariate clearly infer the dimension of the distribution passed to them. One can also usually ...
0
votes
0answers
105 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
106 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
105 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
98 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
1answer
95 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
96 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
285 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
89 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
242 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
75 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
89 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
496 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
104 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
146 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
140 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
75 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 ...
23
votes
3answers
556 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
96 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
223 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
119 views

A problem with set values

The following code is just an example to clearly explain my problem. Assume that : ...
4
votes
0answers
115 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
179 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
103 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
167 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
146 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
145 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 ...
13
votes
2answers
880 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
30 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
280 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
196 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 ...

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