# All Questions

61,700 questions
33 views

### The function VertexContract does not work in specific case

I am using the function VertexContract and I am experiencing that it does not work in some specific cases. If I give the graph with EdgeWeights, EdgeLabels and VertexLabels, I cannot contract {2,5} ...
32 views

### Putting legends within the frame of the plot at the desired position

dat1krafull = {{1., 2.61594*^-8}, {10., 7.10017*^-9}, {50., 2.1565*^-9}, {75., 1.6567...
37 views

### How can I plot the 3D diagram of x[t], x[t] and a parameter ηb as the three axes?

I have ploted a 2D diagram with ParametricPlot for the equations. The codes ...
183 views

### Pairwise Scatter Plots with Histograms and Correlations

Has anybody written a function which can scatter plot data with histograms and correlations? Here is an example form MATLAB. This is related but does not print correlations. R has a similar function. ...
106 views

### Visualizing only the chain of a protein and color each residue in Mathematica

Is there a way to visualize in cartoon a single chain of a protein using ProteinData and color the residues by its chemical properties e.g. hydrophobicity, acidic and basic ? The issue here is that I'...
65 views

### Generating all connected graphs from a set of n-valent vertices?

I would like to have a function generateConnected[list_] that, given a set of vertices with pre-defined valence (number of outgoing edges) generates all possible ...
81 views

### How can I plot a growth curve? [on hold]

How would I draw a plo4 of the function $\qquad dN/dt = r\,N(t)$ in Mathematica? $N(t)$ is the number of individuals in the population at time $t$ and $r$ is the growth rate.
50 views

### Interpreting the solution for a nonlinear system in a matrix form

I have an issue of how to interpret the solution of the following nonlinear system in a matrix: $F=PX^{-1}AX+wL$ where $w>0$ is a scalar, $F=(F_1,F_2)$, $P=(P_1,P_2)$, and $L=(L_1,L_2)$ are all a ...
98 views

### Making an Email Address Validator

I wanted to make a simple email address validator using StringMatchQ. This was my first attempt: ...
98 views

### How do we optimise double Tables?

I have made the following code which I shall explain it in two parts: First Part: ...
20 views

### Numbers not multiplied out in the numerical expansion

I have a Mathematica notebook file with some functions that I need to evaluate numerically. However, for some values of certain variables Mathematica does not give me a result as just one number, but ...
31 views

### How to filter audio to get best results in correlation?

I am trying to recognise the alphabetical letters by saving some data of records of me and others saying each letter, then comparing a test audio not contained in the data to each letter using the ...
45 views

### Mathematica suddenly became extremly slow (Windows 10)

I restarted my computer, and Mathematica became eeeextremly slow. It takes like 5mn to make calculations it used to do in 3seconds. I have seen Suddenly mathematica is very slow when screen is ...
64 views

### How to read in and assign values from a txt file?

I have a text file that I would like to import into Mathematica - after searching around the internet, I can't seem to find any pages that explain how to do this: The text file containes these four ...
693 views

### How can I get edges to bend to avoid crossing?

I want to generate a layered drawing of the Hoffman–Singlelton graph. As an example of what I want, here is a layered drawing of the Petersen graph: Now if I right click on the output of ...
27 views

### Change input filename according to ticker

I want to import a series of files with similar filenames that change according to a "ticker". An example is filenames A1_data.dat, ...
81 views

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### Gyrating particle transmission through rectangle: NIntegrate or something faster?

I need a function that tells me, what transmission a gyrating particle has through a rectangular aperture if you consider all phase angles. So for a specific guiding center position and gyration ...
90 views

### How to find maximum/minimum in ContourPlot?

The ContourPlot of Sin[x^3 + y] - 2 Cos[x y]==0 has a maximum around (-1.8,-2.3), see figure ...
56 views

### Create an array whose index are given by a list (not necesseraly regularly spaced)

I would like to create an array f containing n indices. The label of those indices is stored in a liste of length n, let's call it "list". So I would like to have something like : {f[list[[0]]], f[...
50 views

### How does one use NSum within NIntegrate properly?

If I use symbolic integration for the following: Sum[Integrate[i + x, {x, 1, 7}], {i, 1, 7}] 336 as one can see it gives the answer as it seems to '...
122 views

### Finding the radius of a circle given that it is tangent to both axes and contains (10, 9)

A circle is tangent to both axes in the 1st quadrant of the xy-plane. If the point (10, 9) is on the circle, what is the circle radius?
68 views

### Why is an empty plot produced?

I am trying to plot the values of the functions f[x] and der[x], but I am getting an empty plot. I am new to both Mathematica ...
98 views

### How to link C++ code through the new compiler in V12?

The Advanced Compilation Topics talk in the WTC 2018 shows that one can easily link C++ code through the new compiler technology. This feature seems very useful as one can easily load existing C++ ...
4 views

### Find the shaded part area? [migrated]

Two squares of side 5 and 2 respectively. They are touching each other. Diagonals of the square are joined. find the area of the shaded part?
60 views

### Not getting expected answer for double integral [on hold]

When the Mathematica processes the expressions shown below, the result is 0, That is not the correct answer. Please help me understand what the problem is. (0 < x and z < 1) https://1drv.ms/u/s!...
53 views

### Need help in understanding what Extract does

Can anyone explain two examples from the Mathematica Documentation Center reference page on Extract? One is: ...
31 views

### Splitting large matrix in neural network

I'm trying to make a neural network that takes a 16x100x100 matrix and splits it into each 100x100 part, puts each through a dense layer, and then puts them them together once again to form a 16x10x10 ...
37 views

### Error with NSum : it returns NSum::nsnum: Summand (or its derivative) f[n] is not numerical at point n=17

Consider the following example (I had a lot of trouble to find a minimal working example, I think it is compactified enough now). ...
46 views

### Calculation of the average of the values of a column in a matrix

I am trying to have a list of values which corresponds to the mean of the values of each column of a matrix. Here I show a quick example (my current matrix has a dimension of 1000 * 1000) If I have ...
32 views

### Alternatives for chromatic number in graphs

The function IGChromaticNumber in IGraph works great, so well, that I have been able to check the chromatic number of graphs with max degree 12 with over a thousand vertices in a relatively short ...
27 views

### Simplest way to export (and import) definitions?

Consider I have this code : f[1]=2 f[1.5]=6 f[3]=4 What is the simplest way to save the array f defined on those three numbers in a file ? (in my case, I will ...
129 views

### Compute unstable integral with high precision

I want to calculate $$\int_{\mathbb{R}^n} e^{-t_1^4-t_2^4- ...-t_n^4-(1-t_1-t_2-...-t_n)^4} \text{d}t_1 \text{d}t_2 ... \text{d}t_n$$ with the highest possible n. I tried with ...
23 views

### Is it better to convert numerical integrals into numerical sums?

I sometimes deal with integrals that can't be solved analytically to give a closed-form expression, but that can be converted into infinite sums instead. Is there a general rule about whether ...
46 views

### Why doesn't ClearAll[“Global'*”] remove all variables? [on hold]

Consider the following code : In[19]:= a = 2; In[20]:= ClearAll["Global'*"]; In[21]:= a Out[21]= 2 As you see, the variable a hasn't been resetted. Why ? ...
35 views

### Stacked Bar Chart with a bar showing the forecasted quantity and the real quantity as the part of this bar

I was looking for a way to make a stacked bar chart, where a bar shows the forecast and the real quantity as the part of the forecast. So, if the forecasted quantity is 10 and the real quantity is 5, ...
725 views

### Generate and graph the Recamán Sequence

I was surprised to see that we don't have any posts that mention the Recamán Sequence, so I figured I should post it as a challenge. By definition, $a_0=0$ and $a_n=a_{n-1}-n$ if the r.h.s. is ...
56 views

### Parallelization command possible bug

In the following Mathematica compiled program, 3 persons take turns in a fair Russian Roulette Game with 1 bullet in the 6th chamber and we find the probabilities of each person being killed after 1,...
66 views

34 views

### Conditions to make unitary a given matrix

Suppose I have some symmetric matrix W = {{c[1, 1], c[1, 2], c[1, 3]}, {c[1, 2], c[2, 2],c[2, 3]}, {c[1, 3], c[2, 3], c[3, 3]}}; where the c's are complex and I ...
463 views

### How do I find and plot the intersection of these three surfaces?

I know how to find the region of intersection of these cylinders using integration, but how would I plot that in mathematica? This is what I have ...
88 views
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### Aligning plot axes of multiple figures results in different size of the FrameTicks

I defined a new FrameTicksStyle, but their size is changed when more than one figure are stacked vertically. However, the size is accepted when figures are stacked ...