# All Questions

356 views

### Plotting boundary of piecewise function in ContourPlot

I am trying to do a ContourPlot of the following function: ...
136 views

### What kind of PDF files that MMA does not read (import)

SORRY that I have tried 5 different files, which were too complicated for MMA to import. So I thought that maybe it just does not read any files. But I was wrong. So edited my question. In here, is a ...
167 views

### Is Mathematica's (v10.0.2) NetCDF exporter broken?

I'm trying something very simple, namely: Export["file.nc", {"Datasets" -> {"seqs" -> {"AAA", "BBB"}}}, "Rules"] And getting Java errors about "illegal ...
143 views

### Pattern Match and Replace Expression involving Pure Function

Let's say I have an expression that in held form contains a pointer to a function. expr = Hold[2*{"FUNCTION1"} + 5]; ...
130 views

### How to adjust the animation rate in a Manipulate environment

The enclosed code is a simplified version of the "Make Your Own Solar System" demonstration. How do I remove the manual Faster and Slower animation controls and add code for a permanent very slow ...
239 views

### Trying to Figure Out how to work with datasets & Classify[] and Predict[]

I'm new to Mathematica and I'm a bit overwhelmed. I have always used R for my statistics problems. Now that I'm trying to replicate what I do in R in Mathematica I'm making little progress. For ...
351 views

### Multiplying block matrices

I have a 2*8 matrix A, and a 2*8*2 matrix B. So B[[1]] and B[[2]] are both 8*2 matrices. I need a neat way to multiply A by B so that the first list in the result is A.B[[1]] and the second list ...
166 views

### Regular Polyhedra coordinate points generation

Is it possible to get all points on a Polyhedron surface using two surface parameters, say $\phi,\theta$ spherical co-ordinates? Just like in ParametricPlot3D, can we start with PolyhedronData ...
284 views

### Integration of a Rational Function returns RootSum[]

I am trying to solve an integral given below: Integrate[r^2/(-α r^3 + r^2 - 2 m r + Q^2), r] but since coefficients of this cubic polynomial are as parameters, ...
180 views

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74 views

### Partitioning a list in n sublists with constrains in their sums

Is there a way to put cluster level limits on clusters? For example, if I run: FindClusters[{1, 2, 3, 4, 4, 6, 7, 10}] I get back two lists, ...
558 views

### Moving polygon on path curve to create 3D shape

How can I move some polygon list = {{0, 0}, {0, 15}, {7, 13}, {2, 13}, {2, 5}, {5, 5}, {5, 3}, {2,3}, {2, 0}}; Graphics[{Black, Polygon[list]}] so it follow some ...
190 views

### Test for group isomorphism and construct automorphism groups

MMA has some support for group theory, allowing representation of any finite group as a subgroup of $S_n$. It does not seem to have a function for testing whether two finite groups are isomorphic. Is ...
86 views

### Font rendering difference between .jpg & .pdf [duplicate]

I have some planar graphics involving lines and text, produced by Line[] and Text[], accepting the default font on the latter. ...
110 views

### Using Fold to show stages of Euler product formula

I would like to recursively replicate each stage of the Euler product proof. This does it: ...
416 views

### How to prevent instability blow up in NDSolve?

I have the following code to solve a PDE: ...
172 views

I already found this Example but i want to add a description and the individual vectors as in the picture. My approach so far: ...
578 views

### Find the minimum integer r such that $(10^r - 1)/37$ is an integer

I know Element[(10^r - 1)/37, Integers] tests the condition. So what is the command that gives me the minimum integer value r ...
276 views

### Issue with integration from 0 to infinity with constants [closed]

I am trying to take the integration for $\int_0^{+\infty}e^{-\alpha t}sin(\beta t)d t$. Here is a screen shot of what I did: The solution to this integeation should be ...
101 views

### Simplify BeginPackage with Package of Packages

I have a group of Packages that I use to create a lot of other Packages. Let's see an example: ...
308 views

### Picking items from a list

There's probably a Mathematica primitive to do this, but I don't know what it is...suppose I wanted to construct a list of all integers from $1$ to $n$ that were not divisible by $12$, and that were ...
41 views

### Default value behaves differently when used in Function and when used with Cases

Consider this example: Cases[{4, x, 5 a , 6 x}, x_.*a_ :> x] (*{1, 1, 5, 6}*) It is clear that the _. took 1 as a ...
190 views

### Input of ions and compounds in Wolfram's Mathematica [closed]

I want to use Wolfram's Mathematica to see some data about certain ions. I don't know how to write the chemical's compounds or ions full names, so that at this time I need to write its "formula". ...
255 views

### Issue in NDSolve and unknown error

I try to solve a simple BVP: $A {v}''(t)+B v(t)=f(t)$ where $A, B$ — $5\times 5$ matrices, $f(t)$ — 5-dimentional vector-function with the use of NDSolve. Each component of $f(t)$ is a combination ...
163 views

### DSolve versus DSolveValue [closed]

I've just discovered the new command DSolveValue in Mathematica 10. Is this new command now the preferred instead of DSolve? Is it the better command to teach to students? Same question for ...
230 views

### Rescaling and reorienting Matrix Plot axes

I have implemented a numeric Laplace Solver in C++ and am trying to graphically represent the validity of my method. I have outputted the grid from C++ and imported it into Mathematica to get the ...
83 views

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165 views

### Manipulate: ListPlot and Labeling

I am trying to make a set of scatterplots where the 'u' value is a year. I am using the following dataset: ...
103 views

### PrimitiveRoot function

The function PrimitiveRoot[n] claims to return the smallest primitive root of n. I believe this is not true. For example ...
197 views

### How to Update 2D List based on a binary array

I have 3 lists: numbers = {{1, 2}, {3, 4}, {5, 6}}; toUpdate = {{1, 0}, {0, 0}, {1, 1}}; newValues = {{10, 20}, {30, 40}, {50,60}}; I have to update the list ...
709 views

### Rendering thousands of points

I am trying to render an image with some 120,000 Points. Technically it's just 10,000 points, plus their reflection, plus 5 rotations of both of those sets, but I'm ...
775 views

### Implement the Bisection algorithm elegantly and easily

Description: Rencently, I have finished my course Numerical Analysis, so I'd like to implement many algorithm that I have learned from that course.By this practice, I hope that I can improve my ...
42 views

### hold specific pattern in symbolic calculation

I encounter some questions when I try to simplify a symbolic expression using Mathematica. For example, I got an intermediate expression ...
215 views

### RegionPlot of an area inside a polar plot (or its equivalent parametric plot)

Let' s take a most simple example for a polar plot, the Archimede's spiral. ...
77 views

### Association without an associated value

Sometimes, we only need to store the keys which will be checked whether certain keys exist in the data structure(corresponding data structures in C++ are std::set ...
162 views

### Create a function which gets a function and a x as argument and returns the y [closed]

After a few hours and lots of tries, I am hoping that someone could give me a solution to my problem. I want to have a function, which gets a function and a value as arguments. The function should now ...
72 views

### Finding if a graph contains an even cycle

I am looking for a simple boolean-like function which could check if a graph contains an even cycle. I'm aware there is ExtractCycles but I'm looking for a true/false output than a list of cycles.
65 views

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335 views

### Is it possible to draw a curved edge between two vertexes of a graph? [duplicate]

The following code generates a graph. ...
228 views

### Implement functions that depend on previous value in NDSolve

I want to numerically solve a system of differential equations in Mathematica, say for example $\frac{dx}{dt} = f(x,y,t) \\ \frac{dy}{dt} = g(x,y,t)$ for $x(t), y(t)$. However, the functions depend ...
101 views

### Importing a text file

I have a *.txt file with values like so: 0 2 4 3 4 2 the position in this huge *.txt ...
498 views

### NDSolve and maximum number of steps reached

I am newbie at Mathematica but I need to solve differential equation so I took my chances and tried to use this powerful tool to solve this equation: \frac{d}{dx}\left([\cos(2\pi ...
105 views

### Bug in ExportString with Associations as ExpressionML?

Bug present in 10.0.2 or earlier, and persisting through 10.3 If I try to export this toy code as ExpressionML or just XML: ...
212 views

### Find 2 points in a normal distribution with these given properties

I would like to find a and b. How should I code this in Mathematica? What I did wrong? ...
101 views

### universal precision control in Mathematica

There are many ways to control precision in Mathematica, such as PrecisionGoal in specific build-in commmands or SetPrecision to some variables. I got two questions below, (1) If I do not set any ...
576 views

### Plotting piecewise functions

I have a list of N functions called functionList. N can be any number. Also, I have a list ...
67 views

### Data file organized in strings

I am working in a data set : The original question, They are strings of thousands stars,and each one contains a lot of parameters, and the following item is called identifies, they are the names ...
159 views

### LetterCharacter for Cyrillic symbols

Why does the code StringMatchQ["ы", LetterCharacter] return False? Probably because: ...
I often run into a situation where I'd like to generate a set of permutations with at most $n$ elements (here $n = 5$): ...