0
votes
1answer
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 ...
0
votes
0answers
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: ...
1
vote
2answers
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 ...
2
votes
1answer
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 ...
0
votes
0answers
33 views

DotProduct returns an un-evaluated expression

I am stuck on the following problem: ...
0
votes
0answers
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? ...
1
vote
0answers
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". ...
0
votes
0answers
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 ...
2
votes
0answers
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 ...
2
votes
1answer
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 ...
2
votes
1answer
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: ...
1
vote
0answers
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. ...
2
votes
3answers
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 ...
7
votes
2answers
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 ...
5
votes
2answers
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 ...
1
vote
1answer
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 ...
0
votes
0answers
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. ...
1
vote
2answers
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 ...
1
vote
3answers
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 ...
1
vote
1answer
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.
0
votes
1answer
40 views
4
votes
1answer
167 views
3
votes
2answers
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 ...
1
vote
1answer
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 ...
2
votes
1answer
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 ...
0
votes
0answers
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 ...
4
votes
0answers
49 views

Bug in ExportString with Associations as ExpressionML?

If I try to export this toy code as ExpressionML or just XML: ...
1
vote
3answers
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? ...
0
votes
0answers
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 ...
4
votes
4answers
194 views

Plotting piecewise functions

I have a list of N functions called functionList. N can be any number. Also, I have a list ...
0
votes
1answer
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 ...
7
votes
1answer
106 views

LetterCharacter for Cyrillic symbols

Why does the code StringMatchQ["ы", LetterCharacter] return False? Probably because: ...
0
votes
0answers
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 ...
1
vote
1answer
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 $n = 5$): ...
0
votes
0answers
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 ...
7
votes
2answers
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 ...
1
vote
1answer
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 ...
-2
votes
0answers
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, ...
1
vote
1answer
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, ...
2
votes
1answer
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 ...
2
votes
4answers
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 ...
1
vote
1answer
20 views

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

LogLikelihood[MultinomialDistribution[100, {0.2, 0.3, 0.5}], {{10, 20, 70}}] -12.8338 No problem at all. ...
0
votes
0answers
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 ...
0
votes
0answers
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 ...
-1
votes
0answers
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 ...
0
votes
1answer
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 ...
-5
votes
0answers
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.
0
votes
1answer
37 views

Integral for piecewise function inconsistent with the usual way

I have the following piecewise function: ...
0
votes
1answer
64 views

Sum Over Multiple Indices part 2

Recently I asked this question as I was trying to see how to write a particular Identity. I asked about how to write the following sum: ...

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