13
votes
1answer
496 views

Morphological Filtering in 3D to produce skeletons

Context As a follow up of this question and that answer, I would like to identify the special lines separating 3D watersheds. These are useful in the context of astronomy to identify the ...
2
votes
1answer
385 views

Dynamic graph construction and visualization (Watts' “Small Worlds” α-model)

I need some help in creating a Mathematica program for building and visualizing Watts' "Small Worlds" α-model. This is a variant of the more known (and much more simple) β-model (also known as ...
1
vote
1answer
74 views

Export data from NDSolve when they meet a certain condition

I need to export to a txt file the data from the following system of equations: ...
3
votes
1answer
117 views

Recursion when randomizing elements in a list

I want to randomize certain elements of a list; Since the code list = {a, b, c, d, e, f, g}; list[[{1, 3, 5}]] = RandomSample@list[[{1, 3, 5}]]; list works fine, ...
7
votes
2answers
600 views

Generate Random Text within a Rectangle

I would like to generate images such as the four below. That is: some text of different length fit within a Rectangle[] using ...
2
votes
2answers
183 views

Constraining a random function

This question is a follow-up from here. I have a function that generates a list of correlations between some random variables: ...
0
votes
1answer
203 views

Generate Random 3D Network using GraphPlot3D and loop

Instead of writing all this out I want to do the same thing with a loop and be able to manipulate n and k. The idea is to create a randomly generated network where n is the number of nodes and k is ...
15
votes
3answers
3k views

Create triangular mesh from random list of points

I have a list of points. I would like to take these points and create a mesh of triangles from them, making sure triangles don't overlap. So here's a list of points: ...
6
votes
1answer
152 views

How to make several DateListPlot have the same scale?

I want to plot some weather data series. Unfortunately the series were collected in different episodes, from which some overlap. I would like to plot them as different plots in a column, but with ...
5
votes
1answer
176 views

Drawing disk with coordinates from NDSolve

I have simple Manipulation expression, but continuously getting error Coordinate {x[0.], y[0.]} should be a pair of numbers, or a Scaled or Offset form. I assume that something is wrong with ...
3
votes
1answer
135 views

Dynamic interaction with a 3D plot

I have a function: C = 0.0625 + 0.0008*X - 0.0232*Y - 0.0157*Z + 0.0059*X^2 + 0.0112*Y^2 + 0.0160*Z^2 - 0.0063*X*Y - 0.0243*X*Z + 0.0211*Y*Z This equation ...
4
votes
2answers
295 views

Epilog with text not shown

I use the Epilog option in order to print in the vertical axes a label between 0 and 20 as follows ...
3
votes
3answers
345 views

Coloring random points in an annulus

I have found the following random generator to generate points in an annulus in stackoverflow on stackoverflow ...
2
votes
1answer
138 views

How to label vertices in a grid with random integers?

I would like to assign each vertex a random number with the minimum bound equal to the smallest vertex and the maximum equal to the value of the largest without repeats. For example, in a 20x20 grid, ...
4
votes
2answers
268 views

Repeatedly randomly redrawing part of a random sample that matches a certain criterion

I would need some (a lot of) help to improve/rewrite some code. Since my real problem is a bit too complicated to explain, I'll try to show a simplified scheme of what I want to achieve. I create ...
8
votes
1answer
961 views

How can I randomize order of elements in a list?

Is there a straightforward way to go from an ordered list like: ord = {a, b, c, d, e, f, g, h} to a disordered list like: ...
4
votes
2answers
190 views

Fill curve betwen specified abscissa points [duplicate]

I am plotting the Maxwell-Boltzman distribution of molecular speeds. I want to be able to select a region to integrate using a manipulate function. Then I want to have that same region filled in on ...
1
vote
0answers
42 views

Default starting location of “Save as…” dialog in OS X [duplicate]

In the answer to this previous question, user Szabolcs says On OS X (I'm using 10.9 and Mathematica 9) the file chooser dialogue will remember the last location you used. So if you Save/Open ...
2
votes
1answer
178 views

Convert matrix of strings to matrix of numbers [duplicate]

I have 101 files each with a lot of data. from C output. (.out files) I have imported them to Mathematica 9. However, Mathematica reads the data from each file as an element of a table. So I used ...
2
votes
1answer
89 views

How can I set a RadioButton to invoke an action, like a Button can?

In Mathematica one can create a Button which, when clicked, invokes an action. For example... ...
15
votes
1answer
1k views

I failed to solve a set of one-dimension fluid mechanics PDEs with NDSolve

The fluid here has been assumed as single component perfect gas i.e. it obeys the equation $p=ρ R T$, the thermal conductivity is assumed as a constant, so the equation set is: ...
1
vote
1answer
309 views

Generate random nxn matrix with all negative eigenvalues

I need to generate an nxn matrix with random entries, but I also need all of the eigenvalues to be negative (real or complex doesn't matter). I have: ...
1
vote
1answer
86 views

Getting unwanted solution from Solve

I am solving the simultaneously equations $\quad \quad x_7=0$ and $\quad \quad 6x_4x_5+6x_3x_5x_6+zx_4x_7^2+zx_5x_7^2=0$ with Solve. Here, $z$ is an unknown ...
1
vote
1answer
48 views

Unexpected behaviour with GraphIntersection and GraphDifference

I run into some unexpected behaviour of GraphIntersection and GraphDifference. Behaviour is the same for both so the example is only on the GraphIntersection: Suppose I have two lists of directed ...
3
votes
2answers
750 views

what to do when NSolve does not solve

f = 696.1125540355472 + 3.9668099604385043 x + LogGamma[1 + x] - LogGamma[169 + x] Plot[f, {x, 0, 10}] Solve[f == 0, x, Reals] NSolve[f == 0, x] I know that the ...
2
votes
1answer
344 views

ParametricNDSolve KKT Constraint Directly

I am trying to directly solve for an optimal control using Pontryagin Maximum, where H is the Hamiltonian, in the presence of a KKT constraint. The constraint is ignored. I am wondering if a direct ...
5
votes
2answers
360 views

Converting image data to array

I'd like to convert these images to a list or array in order to graph them. I know some rows are unreadable, but it doesn't really matter. So I tried using ...
5
votes
1answer
366 views

Very serious multiplication bug when subscripts are used

I have found a serious bug in Mathematica 10.0.1.0 on mac os x. See the attached screenshot. It is applying the square root to the Mpc. I am very shocked by this. Does anyone know how to avoid this ...
3
votes
1answer
105 views

Vertical direction in images

Mathematica's relatively new Image structure and related functions are very useful, but it is a great disappointment that they adopted the convention that the first row is at the top of the image. ...
3
votes
1answer
1k views

Proper way to run a Mathematica script (-script vs -run vs MathematicaScript vs <)?

Suppose I have a Mathematica script called test.m. There at least 4 ways to run this from the terminal: ...
2
votes
1answer
288 views

Choosing The Best Fitted Probability Distribution Model

The following Example 20 Obs and i used Goodness of fit test with Exponential distribution, another time with Weibull distribution and third time with Pareto distribution .All of them are significant ...
1
vote
1answer
227 views

Estimating Confidence Interval Variance covariance matrix from weibull distribution

In The following Example 50 obs . I estimated distribution parameters (by point) but *i want to estimate parameters by confidence interval and calculate covariance matrix i need help * ...
4
votes
4answers
241 views

Sublist pattern matching

Is there any way to simplify the following pattern: {p___, {a___, x_, x_, b___}, q___} :> {p, {a, x, b}, q} Ie. where I remove duplicated elements within ...
0
votes
1answer
231 views

How to work with decimals (e.g. 0.95) instead of fractions (95/100) and get the same result

In my code I have a function, F, that depends on several parameters, say a,b,c: F(a,b,c). I need to give a grid of values to a,b and c to obtain the value of F. My grid of values are decimal ...
17
votes
3answers
541 views

Applying different functions to different columns of a Dataset

Suppose I have different functions: Total, Mean and Max and the following ...
1
vote
1answer
575 views

Solving Fredholm Equation of the first kind [duplicate]

I want to numerically solve Fredholm integral equations of the first kind, equations of the form $$g(t)=\int_a^b K(t,s)f(s)\,\mathrm{d}s$$ where we know the functions $K(t,s)$ and $g(t)$ and seek to ...
3
votes
2answers
110 views

The conflated two uses of SameTest within Intersection

Intersection works as expected in this case... a = Range[1,5];b=Range[3,7]; Intersection[a,b] giving... {3,4,5} However if ...
2
votes
3answers
66 views

Reconstructing an expression [duplicate]

I have a nested expression like this one expr = Tan[Sin[Cos[x]]]; I can deconstruct it with ...
3
votes
1answer
201 views

Importing data from Matlab, using data in “NSolve” and send the results back to Matlab

I have generated an image processing code in Matlab. It has several subroutines and in one of them, I should solve a system of 7 nonlinear equations. I use "fsolve" in Matlab to solve this system, ...
1
vote
0answers
147 views

stacking images [closed]

I would like to take a series of night sky photographic images taken sequentially and enhance dim stars in a single image. This is a standard function in astronomical image processing packages, but I ...
7
votes
3answers
408 views

Spacing the elements in a bar chart with error bars

In the Add-Error-Bars-to-Charts-and-Plots How-To in the Mathematica documentation, a function ErrorBar is given: ...
5
votes
2answers
157 views

Non sequitur in documentation of MemberQ

Mr.Wizard's question about MemberQ and FreeQ got me to re-read the documentation for those functions. I find I don't understand ...
1
vote
1answer
156 views

How to evaluate complex numerical integral in mathematica?

I have an integral of the form \begin{align} F(\omega) = \int_0^{\infty} f(s,\omega) \mathrm{d}s \end{align} which I would like to numerically evaluate and plot for a range of $\omega \in ...
2
votes
1answer
125 views

Meaning output ANOVA post hoc tests

I am carrying out an ANOVA in Mma, and I wanted to apply a post-hoc test, but I do not understand the output that is given. It says e.g. Model-> Duncan, {4, 5} ...
3
votes
1answer
353 views

Find the NullSpace of a matrix whose determinant is “almost” zero

If $A$ is a matrix such that $\det(A)=0$, it is easy to get a basis of the kernel of $A$ with NullSpace[A]. Now let's consider a matrix $B$, function of a ...
0
votes
3answers
244 views

Importing multiple files with a loop

I have 101 files with data that I want to import into Mathematica. All the file names are numbered as follows datafile.20.0000.out, datafile.20.1000.out, datafile.20.2000.out and so on. I used the ...
6
votes
1answer
2k views

Mutual Information involving two matrix states

I basically retrieved the following technique of evaluating the mutual information involving two matrices from this site at http://bmia.bmt.tue.nl/People/BRomeny/Courses/8C080/default.htm The ...
16
votes
3answers
5k views

How to generate random directed acyclic graphs?

How to programmatically build random directed acyclic graphs (DAG)? I know about the AcyclicGraphQ predicate and the ...
15
votes
3answers
652 views

How to Import random elements of huge data files

I am calculating huge data files with an external program. I would like then to import the data into Mathematica for analysis. The files are 2 columns and up to many millions of rows. So for ...

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