# All Questions

15 views

### Issue with integration from 0 to infinity with constants

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 ...
15 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: ...
51 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 ...
17 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 ...
33 views

### DotProduct returns an un-evaluated expression

I am stuck on the following problem: ...
40 views

### Symbolic optimisation in Mathematica

Mathematica does not give me a closed form expression for this; though FindMinimize works well in giving me a numerical output. Can someone help me in getting the symbolic output? ...
25 views

### Input of ions and compounds in Wolfram's Mathematica

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". ...
30 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 ...
29 views

### DSolve versus DSolveValue

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 ...
42 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 ...
50 views

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60 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: ...
36 views

### PrimitiveRoot function

The function PrimitiveRoot[n] claims to return the SMALLEST primitive root of n. I believe this is not true. For example PrimitiveRoot[18] returns 11, yet 5 is the smallest primitive root of 18. ...
111 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 ...
302 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 ...
179 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 ...
22 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 ...
51 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. ...
50 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 ...
104 views

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

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 ...
41 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.
40 views

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167 views

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

The following code generates a graph. ...
69 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 ...
67 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 ...
60 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 ...
43 views

### 3D coordinates system issues [on hold]

I have some trouble about 3D coordinates system in mathematica and Image3D[] Suppose that I have a grid of 3D points. Each points represents the center of a voxel (3D pixel) I have used this function ...
49 views

### Bug in ExportString with Associations as ExpressionML?

If I try to export this toy code as ExpressionML or just XML: ...
131 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? ...
38 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 ...
194 views

### Plotting piecewise functions

I have a list of N functions called functionList. N can be any number. Also, I have a list ...
53 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 ...
106 views

### LetterCharacter for Cyrillic symbols

Why does the code StringMatchQ["ы", LetterCharacter] return False? Probably because: ...
86 views

### Spherical harmonic decomposition of 3D shape

Suppose that we have a binary grid of voxel of dimensions 2R*2R*2R. We define a sphere of center {R,R,R} and radii R. So, the voxel grid is treated as a binary function, χ, defined on the set of ...
51 views

### Generating permutations of at most 'n' elements, and where a specific subset of elements always appears

I often run into a situation where I'd like to generate a set of permutations with at most $n$ elements (here $n = 5$): ...
54 views

### How well does my function fit data? [duplicate]

I'm trying to find the best fit to some data that I generate with fortran. Theoretically the data must obey the law I*Sin[x/2]^-2, where I=constant/area. So I used ...
167 views

### Definite integral incorrectly giving a nonreal value

In Mathematica 10.0, when I enter N[Integrate[Sqrt[1+x^3],{x,-1,3}]] , I get a nonreal value. (I.e., the imaginary part is nonzero.) Why? This arose when I ...
66 views

### Getting code from the Wolfram Demonstrations Projects [on hold]

I saw from mathematica's website, there is a fantastic project about the 2D Riemann Sum. Riemann Sums For Functions of Two Variables I want to see the similar effect in my Mathematica (with ...
54 views

### Loop construction

I would like to solve a linear system using the Thomas algorithm, as explained in the picture below. I tried to solve it writing each entry using its definition (3.53). But, if the matrix is larger, ...
79 views

### Plot multiple solutions of a system of differential equations with different values of constant c by using NDsolve

I am traying to solve system of differential equations with different values of constant c then plot the solution with different values of the constant c. where c= 2.2758, 2.04822, 1.82064, 1.59306, ...
105 views

### PairwiseScatterPlot with histograms along the diagonal

The built-in function PairwiseScatterPlot has been discussed for example here: Scatterplots for subsets of multivariate data [Updated]. However, I find it not very ...
346 views

### Random real numbers that sum up to specific value

In here, it works with "Integer". What if I want 5 positive real numbers that sum to 1? RandomChoice[IntegerPartitions[100, {5}]]/100. That will work. But only ...
20 views

### LogLikelihood[MultinomialDistribution[],{}] Not working?

LogLikelihood[MultinomialDistribution[100, {0.2, 0.3, 0.5}], {{10, 20, 70}}] -12.8338 No problem at all. ...
23 views

### How to decrease the time complexity of this recurrence relation? [on hold]

I have been trying to solve a problem which appeared in ACM ICPC 2014 Asia Regionals and came up with the following recurrence relation Here is the code for the implementation of O(n*k*l). where l ...
18 views

### How to configure Linux Remote Kernel in V10?

I have read couple of posts and it seems that Mathematica has changed some settings over the years. So I will make the title explicit, so it is clear I want to setup remote kernels in V10. My ...
26 views

### FullForm in Linux Command Line

Maybe I missed something, but I am looking for a way to get the output of FullForm in Command Line under Linux (Debian). When I run FullForm[1+1] it answers ...
31 views

### To get a certain value of NDsolve of the solution [on hold]

I need to solve the differential equations for different values. Once it is solved I want to take, for example, x[29] for each initial condition and plot it as a function of this initial conditions. I ...
32 views

### finding the canonic equation of a ellipse with steps [on hold]

ellipse directriz x+y-10=0 dierectriz x+y+6=0 vertex (3,3) we want to find the canonic equation. the ellipse equation in the coordinate system x-y please show me steps.