6
votes
1answer
175 views

Large scale linear programming (Data imported from .mat file)

I tried to run a large scale linear programming with mathematica. I entered the code below: ...
1
vote
1answer
190 views

2D Markov Process

I have a homework project. I need to analyse a gambler's ruin where there are 6 possible outcomes of every wager with corresponding probabilities and payoffs and the gambler may vary the wager (say ...
0
votes
1answer
144 views

Applying a general formula

We are a group of students who are struggling with transforming this formula to run in mathematica. In fact there are many formulas that we are struggling with, but if we are able to see how this is ...
3
votes
1answer
111 views

How to Override the Head of a Symbol

I was wondering if it is possible to override the head of symbols/operators. As a motivating example if I run: Then Ket will be returned. But lets say I want Bob to be returned instead of Ket. Is ...
3
votes
2answers
188 views

Multi-Fitting with Nonlinear model

I want to fit experimental data by the H-N model. Here is the H-N model: $$\text{EHN}(T)\text{=}\text{E$\infty $}+\frac{\text{E0}-\text{E$\infty $}}{\left(1+\left(i \omega\tau(T_g)10^{-\frac{\text{C1} ...
7
votes
2answers
208 views

Behavior of Reduce with variables as domain

When using Reduce, I accidentally put a set of variables as the domain. To my surprise, it not only seems that Reduce expects ...
-3
votes
2answers
126 views

Find the value by using FindRoot command [closed]

The equation x^4-3 x^3 = cos(3x)+3 has two real solutions on the interval from -10 to 10. Lets call these two solutions r and s. Use Mathematica's FindRoot command to find r and s. Now let M equal the ...
0
votes
2answers
120 views

How to obtain the form of sin(nx) and cos(nx) from the result of FourierSeries [closed]

How to obtain the form of sin(nx) and cos(nx) from the result of FourierSeries[]. For Example, $$\text{FourierSeries}[x,x,5]=i e^{-i x}-i e^{i x}-\frac{1}{2} i e^{-2 i x}+\frac{1}{2} i e^{2 i ...
4
votes
0answers
217 views

Does Mathematica compute free-form-input on Wolfram servers?

I've just started to use Mathematica and I'm using the free-form input a lot. The computation time for simple problems seems to take a lot of time and my CPU isn't really used at all. I first thought ...
1
vote
3answers
114 views

Difficult parametric function

I've got this strange parametric function and I want to implement it on Mathematica. I know that I could use Excel and calculate it, but my database is quite large and I want to do some reproducible ...
1
vote
1answer
102 views

Naming Excel Sheets automatically

After performing some calculations with excel sheets I end with a tridimensional matrix a to be export to a .xlsx format and a vector q that contains the name of all the sheets (so $Length[q] = ...
0
votes
0answers
57 views

Manipulate: After Changing view of a Graphic, the sliders can't be used anymore

I have a new problem: I have exported my program as a cdf standalone. I changed the view of the graphic and now the sliders cant be used anymore. Very strange... Here is a screenshot: The orange ...
0
votes
1answer
176 views

Why is my PageRank result in Mathematica converging this way?

I am using this technique to find the PR of these 3 pages. It converges to something it shouldn't be. I tried the same iteration in Java and 2 pages come up with 1.333 and the other one as 0.666. ...
6
votes
3answers
421 views

How to make all numbers equal to one in a Series?

I have many outputs of one-dimensional Series expansions for which I am only interested in the general tending with the variable. For example, I would like to be able to transform something like ...
0
votes
2answers
331 views

Exporting Animated gif [duplicate]

I am trying to export an animated gif to my desktop but when I do so and open it, the image doesn't move. I've tried with avi and it works.The only reason that I'm exporting as a gif is to the ...
4
votes
5answers
454 views

NIntegrate::slwcon Problem

I have a problem with numerical integration of this function. Integral value is zero, but NIntegrate[] needs a lot of time to calculate this. Is there any way to ...
0
votes
1answer
108 views

How to faster map density matrix element to make differential equations

I have a time dependent matrix $M(t)$ of $L^n \times L^n$ size and want to write differential equations like D[M[i,j][t],t] = H[i,j][t] Here is my code: ...
2
votes
1answer
233 views

Selecting every last element of a nested list

I couldn't find a similar question so I decided to ask this one. I have a nested list with many sublists of equal length. To make things easier let's say it's like that: ...
0
votes
4answers
220 views

Evaluate function from a table

I want to define list of functions and also use them for evaluation. But this just doesn't work. For example ...
14
votes
4answers
2k views

Semi prime numbers

The high school textbook I am using has the example of semi-prime numbers. They wanted students to find (by "perspiration") all the semi-prime numbers less than $50$ (for a question on set theory). ...
2
votes
1answer
97 views

Intersection does not take list of lists

The function Intersection takes a number of lists (sets) and finds their intersection. However, the precise input is ...
11
votes
3answers
2k views

Speed up ordering digit code?

My goal is given an integer number to deduce if its digits increase (or remain the same) from left to right or not. Example: $1236, 123336$ are both considered numbers with increasing digits, but ...
2
votes
2answers
183 views

Find partial derivatives when the number of variables is unknown

The idea is that I have a defined function of $n$ variables. I want to find out $n$ and get partial derivation for each of variables, Suppose you have a function ...
1
vote
2answers
672 views

Plot3D region bounded by equations?

I have four equations, $$ z = xy \\ z=0 \\ y=x^2 \\ x=y^2$$ I would like to integrate the region bounded by them. Before this, I would like to plot the region they bound, but I cannot seem to find ...
8
votes
3answers
276 views

Pairwise distances of points and classification using GraphDistanceMatrix

The challenge Given $n$ points in $\mathbf{R}^3$ and a cutoff distance, $d$, I would like to determine all pairs of points that are separated by less than the given cutoff distance, $d$, and all ...
4
votes
1answer
224 views

Using Boole to integrate over region

I have a complex and long piecewise function to integrate, so I have written a Mathematica script that cuts the whole range of integration, evaluates the integrand in each region and then integrates ...
5
votes
2answers
204 views

How to “ReplaceAll” using a set of conditional expressions instead of a list of rules [closed]

Suppose that I have two linear functions f[x_] := f0 + f1 x g[x_] := g0 + g1 x and a (possibly rather complicated) set of conditional expressions, obtained ...
0
votes
1answer
51 views

Plotting: Basic Question [duplicate]

I am new user. I am plotting "y = x^3". My "x" domain is "{x, -5, 5}", but then it scales for all "y" values. Is there anyway to zoom in, or have it plot/display a limited "y" range of values? The ...
7
votes
2answers
461 views

Double integral over a parallelogram

Problem: Evaluate the following double integral $$\int \!\!\! \int_D (14 x^2+61 xy+42 y^2)^{3} \, dxdy$$ where $D$ is a parallelogram between these four lines: $2x+7y=6$, $2x+7 y=-6$, $7x+6 y=6$ and ...
3
votes
1answer
79 views

Elegant way to match a list with only certain types of elements

I'm working on learning Mathematica programming for personal edification and am trying to find a more elegant way to do a matching expression which will match only a list containing elements that are ...
2
votes
1answer
137 views

GridGraph layout with added edges

I noticed that the nice symmetric layout of a grid graph gets distorted when additional edges are added to the graph. Is there way to prevent that from happening and to keep the rectangular, grid-like ...
0
votes
2answers
47 views

Application on systems of equations [closed]

Lauren has 20 coins in her piggy bank, all dimes and quarters. The total amount of money is $3.05. How many of each coin does she have?
6
votes
1answer
66 views

How to reset the $ModuleNumber?

According to the documentation, we can reset $ModuleNumber to a positive machine integer. There is even an example in the doc: ...
0
votes
1answer
91 views

StreamPlot Label for General Parameter

I have a simple DEQ: $$y'(t) = y + C$$ for a constant $C$. It turns out that the equilibrium point of this DEQ is $-C$. I can use the StreamPlot command to plot ...
2
votes
2answers
480 views

Generating social network graph from a CSV file

I am new to Mathematica and wanted to generate undirected graph for data sets that show the relationships of organizations with each other. The data is in a square matrix. The cells of the matrix ...
1
vote
2answers
195 views

Sorting lists element by element [duplicate]

I have a problem regarding list sorting. Let's say I have a list of lists obtained using Subsets[], of the form ...
0
votes
2answers
240 views

Generating a random tree of given cardinality, depth, and labeling

For demo, exploration and teaching purposes, I would like to be able (and asking you for help) to generate these special instances of trees: For given: N - number of nodes in the tree D - depth of ...
1
vote
1answer
201 views

Combining Newtonian 3D N-Body Simulation Output and Earth Sphere

I'm trying to figure out how to make a simulation whereby two satellites orbit Earth, but have run into a little bit of a snag. I have a solution to the system of ODEs for the n-body output, and I ...
2
votes
1answer
105 views

How to normalise a line in mathematica

I'm working on creating a line plot from a histogram, as in the following: ...
2
votes
1answer
83 views

Export notebook to HTML produces low resolution GIF

I have equations written in my notebooks as text (the cells set as Format -> Style -> Text). When exporting the notebook to HTML (File -> Save As.. -> HTML) with the GIF option (the default) an HTML ...
10
votes
1answer
317 views

How to efficiently mask an image?

I want to extract/cut out a part of an image. Since my mask is not rectangular I want to set pixels that are not masked to zero (black). My current approach is something like this: ...
3
votes
3answers
427 views

Draw grid lines at multiples of k

Here is a beginner's question: when creating plots with mathematica, I want the grid lines to be at multiples of a constant value. E.g. in the following plot, the vertical grid lines are at multiple ...
2
votes
1answer
140 views

Extract the generating curves from a Graphics3d returned from RevolutionPlot3D

I have a plot g = RevolutionPlot3D[{Sin[t], t}, {t, 0, π}, {θ, -π, π + 3 π/4}]; Is it possible to extract the generatrices (generating curves) from ...
4
votes
2answers
336 views

Recognize simple shapes in an image and color them randomly?

I have an image of polygons built from a polar function (see below). I'd like to color each triangle or quadrilateral a random color. Firstly, I'm not sure how to separate the simple shapes. ...
4
votes
1answer
234 views

How to choose MaxStepFraction for optimal speed of NDSolve

I'm trying to use NDSolve to solve a 1D Schrodinger's equation, and it seems that MaxStepFraction has huge effect on the ...
15
votes
1answer
223 views

The second argument of Signature

I've noticed that Signature can have an undocumented second argument. What does it do? Signature[{1,2,3,4}, ?]
11
votes
2answers
492 views

Plotting time data with axes labels and point labels

I am trying to create a set of commands to automatically create clinical lab value plots. Using time is my major issue here. It is hard to dynamically reference the different point positions to ...
0
votes
1answer
126 views

Re[x] vs. x ∈ Reals in the context of Assuming

Let's say that $x$ is some real valued number $>0$. Are the following commands interchangeable in the context of using Assuming? ...
1
vote
0answers
321 views

When are `If`, `Piecewise`, `Switch`, and `Which` interchangeable and when are they not?

Experimenting with joint dependent distributions via the TransformedDistribution function, I used the following to derive a distribution where the second variate is ...
3
votes
1answer
306 views

A Bessel & Struve functions related integral

I try to numerically compute this integral and I don't figure out why on earth Mathematica is not able to do it. Is my input correct? Does it possibly have a closed form? ...

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