# All Questions

96 views

### Delete rows and columns in a matrix based on the element index

This is a follow-up question from here: Define a 4d matrix without for loop I have a 400x400 2d matrix reshaped from a 4d matrix H(i,j,k,l), ...
23 views

### Recursion and Its Stoppage Criteria

Let there be a recursive function V whose first value is set at 0. How can I find its converged value in such a way that the recursion stops when the difference between the newest and the one before ...
45 views

### recursively structuring a multivariate numerical optimization

Suppose that I want to partition the unit interval [0..1] into four subintervals whose max length is as short as possible. I can ask Mathematica to: ...
33 views

### Silly question about linear transformation [on hold]

I define a $3 \times 3$ matrix tran tran = 1/Sqrt[3] {{1, 1, 1}, {1, ζ, ζ^2}, {1, ζ^2, ζ}} Then to do the linear transformation, I use the following code ...
46 views

### How to find first quartile? [on hold]

I have this set: {131, 130, 130, 126, 125, 125, 123, 123, 121, 121}. I need to find some values, and one of these values is first quartile (...
33 views

### Unable to write to MM3000, stepper motor

Serial interface RS232 control I am using a stepper motor connected with RS232 protocol. But I am unable to write or read. I don't get any errors and I have waited after I open the device and then ...
135 views

### Constrain Locator to specified region

How can I constrain the locator to stay within the region defined by RegionPlot? When the Locator remains within the region, ...
63 views

### Does NDSolve iterate faster in a region where the system being solved is in equilibrium?

I was wondering how exactly the time it takes for NDSolve to iterate through a certain region of the domain depends on the local behaviour of the given system being solved. My guess would be the ...
571 views

### Is there any harm or benefit to Removing unneeded private symbols in packages?

One of the things I noticed is that in typical medium-to-large sized packages, a huge number of symbols are created in the myPackagePrivate context. You can see a ...
23 views

### How to find the longest diagonal if you fold a piece of rectangular paper in half? [migrated]

An 8-inch by 12-inch paper napkin is folded in half three times with each fold resulting in a smaller rectangle. What is the longest possible diagonal for the final rectangle? Express your answers in ...
69 views

### Faster code for calculat in Integral include derivative

I saw this question How I can get faster I tried help that. But I can not understand. I want to write a faster code for: ...
35 views

### Sum over abstract value

My plan is to write a sum over an index. Currently I write Sum[f[OverTilde[q]], OverTilde[q] ∈ Subscript[l, i]] but Mathematica always tells me that "The ...
16 views

### How to stop the kernel between the two input dialog box? [on hold]

I have a code which you could see below and I want the kernel not to pass to the second dialog box until the first dialog box input is entered and hitting OK button. CreateDialog[ Grid[{{"Sonlu ...
60 views

### Duplicate rows with multiple entries

I have a huge dataset, which looks similar to this: ...
48 views

### CDF Player and CloudObjectPrivate Problem

I'm trying to generate a simple Manipulate[] example showing Taylor expansion. However, the following code shows ...
90 views

### OptionsPattern[] taken as a Replacement Rule

I was trying to write my own plot function taking as unit size cm instead of points. I've tried ...
32 views

### Existence of edge in graph

I want to know whether an edge exist between two specific vertex? Is there any function like EdgeExist[g,{v1,v2}]?
22 views

### Hold assumption in Simplify [on hold]

If you type this into Mathematica, PrimeQ[x] It will return False. However, ...
96 views

### Good way to create a similarity / distance matrix for a large dataset

I have a large dataset with rows (100k+) for products and columns for features. Now I want to create a similarity matrix with NormalizedSquaredEuclideanDistance. ...
33 views

### Trying to solve ODE. Need help with error messages [on hold]

With this code I get an error-message: Equation or list of equations expected instead of True in the first argument. Apparently y'[0] == v0 gives ...
53 views

### Create a Dataset object, Association or SparesArray from a matrix [on hold]

I need to make queries and operations on a large dataset. What is the easiest way to add keys to matrix so that it is transformed to a dataset, which can later be used to make queries? Let's take ...
31 views

### Mathematica doesn't save my work [on hold]

When I save my work and close Mathematica, usually it's not saved, it won't save a my work,despite that it asks where to save the file. Sometimes it creates an empty notebook only.
57 views

### Why doesn't Mathematica solve this non linear (fractional) ODE? [on hold]

a1 = NDSolve[{y1''[x] - 0.1 y1[x]^0.25 == 0, y1'[0] == 0, y1[1] == 1}, I get the following errors - Power::infy: "Infinite expression 1/0.^0.75 encountered ...
127 views

68 views

### Why is FindCycle crashing for this graph?

I'm working with a directed graph, previously mentioned in Exporting a high-resolution GraphPlot of a very large graph (65,536 nodes). It can be generated with the following code: ...
161 views

### Is it possible to get the (x, y) position of nodes in a Graph`?

Given a graph... RandomGraph[{20,40}] ...is it possible to retrieve the (x, y) coordinates at which the nodes are drawn? ...
106 views

### Evaluate pure function through round brackets

In have some matrices of pure functions or numbers which I multiply by other matrices or vectors. I would like the functions to be evaluated in the result, but all that I get is something like this: ...