**1.745 performance-tuning questions.**

I have some code I've been using to generate some random geometric graphs as fast as possible.
The boundary conditions on the rectangular domain I am using sometimes interferes with a clean ...

I've opened a question here, which was answered. The code works totally fine for a small set of data. However, for a large set and over many iterations, it will take a long time (in order of 24 hours)....

The first line generates 1050 data points to fit. The second line fits this data to the same distribution. This takes about 100ms on my computer. Doing this with ...

In quantum mechanics, we often want to build operators acting on multiple particles by simply "Kronecker-ing" operators from the single-particle spaces. That is, if I have some matrix $A$ acting on ...

I look for an efficient way to implement a Belief Propagation in Pairwise Markov Random Field.
Each node is a binary random variable, and the unary potential function is
...

I trained a Predict and when I look at PredictorInformation it says evaluation time is less than 1 millisecond per example. ...

I would like to know is it possible to find positions of False in t:
...

I need to find the position of elements in list that are present in close. These are both 2D lists. The code is simple but not ...

Below is the expression I want to optimize, ('I' represent the imaginary unit):ParallelTable[Flatten[Exp[I*n*list]], {n, -10, 10}];as you can see I already ...

The following is a question in regards to the matrix $A$ (originally the zero $4n \times 4n$ matrix) below:
...

The main goal of this procedure is to first rotate an array of 3D coordinate leaving z untouched,finding the positions of tuples with z larger than some value, and then mapping those positions to the ...

I am interested in save a list (the size of the list is two) of numbers in the sparse matrix, but this is not supported.
Maybe you familiar with some workarounds or any suggestion on another data ...

I'm trying to solve this problem
I'm not a Mathematica expert, but my program works perfect when vhartree={0,0,..,0}This is the program I wrote:
...

I'm trying to reset the value of functions $u_{i}$ when they reach a threshold $θ$. Below the threshold, they evolve according to a simple differential equation. The $r_{i}$ resets the derivative to ...

I have a gif Example.gif, and would like to play it in a presentation. I used the following code:-
...

I am interested in updating the values of the sparse matrix. I have a list of matrix element which I am interested in updating and a list of new values. Currently, I do it in the following manner:<...

Given a collection of sorted lists {l1, l2, ...} I need to find the smallest k index tuples taken from these lists by summed ...

In the sparse matrix, we have a list of properties: specified elements, dimension, default, and density. I am interested in getting this data without calculating them again.
For an example, the ...

I am trying to use a recurrence plot to pinpoint the location when a system re-visits a previous point in its phase portrait. The system (a thin liquid film) is governed by a non-linear differential ...

It is well known that we use // Evaluate or Evaluated -> True to get Plot to "see" that ...

Continuing my last question, I am trying to solve 3D Schrodinger equation (with mass equals to 1) and with no potential (I will add a potential later).
The analytical solution for this equation is ...

I am fairly new to mathematica and working my way thru Paul Wellins book on Mathematica programming so experimenting with various language constructs. I was experimenting with ...

I have a huge expression called exp1 which is a function of rr. There are some terms in the huge expression which diverge when I put rr equal to zero. I want to find these terms. Does any one know an ...

Consider a large expression which contains terms like a/x+b/x^2+c x + d x^4 +...-b/x^2 +h x -a/x +...I want to find limit of the expression when x goes to zero....

Given a large list of elements, is it possible to improve Select by parallelizing?
An example: from a 10,000,000-element list of integers between 1 and 10, select ...

I am interested in replacing all elements in a diagonal of a sparse matrix with zero. Currently, I do it in the following manner:
...

I would like to know if there is a way to make Mathematica to use at most certain digit number. For example, Suppose I want to calculate 2*Pi.x=N[Pi]
y=2*x...

I'm trying to search for still lifes in Conway's Game of Life.
An object in Conway's Game of Life can be represented by an array of booleans, say, Array[b, {w, h}]....

This is a follow-up question from my previous question. What I was trying to do was to plot the contour plot of the following given scalar function.
$$\Phi(x,y,z)=\int_{h=-a}^{a}\int_{k=-b}^{b}\int_{...

I have an equation which I need to triple integrate over a unit cube. The equation is
...

Context:
As a possible approach to Goldbach's Conjecture, we create two lists of least/greatest prime factors of the odd numbers. The lists are A090368 lpf and A076565 gpf. We get symmetric ...

I have a sparse matrix, and I am interested in find k largest elements and their positions in the matrix.
I do it in the following manner:
...

I look for an efficient way to implement a Pairwise Markov Random Field.
I have implemented a homogeneous (i.e., unary potential is a similar function in all nodes, and pairwise potential is a ...

It appears that Mathematica tries to list the folder that you're typing into an Import[] statement. Since I'm working with folders mounted over sshfs and they ...

I've worked for several days trying to get this code to run faster. The imported data is 15MB.
...

I've been writing a ServiceConnection to the OEIS and one thing I need to do is import large sequences of numbers, like this one.
My first though for this was to ...

I am working on the Ising 2D model in Mathematica and this is currently my Metropolis sampling function:
...

I am interested in calculating the cosine distance between each pair of the element of a sparse matrix. I am using the built-in function DistanceMatrix with the ...

I would like to find the solution of an equation containing a slow functionFindRoot[func[x, onsideS, hoppingS, 0.01] - (1/E) == 0, {x, 1,10}]for different ...

I'm a big fan of Chop. It's fast and useful in pre-rounding transforms and things
Unfortunately it also necessarily unpacks a real ...

Edit:
Okay, my question was viewed quite a few times but not answered so I assume I phrased/presented in a confusing way. I'll try to rephrase my problem to make it more accessible because luckily I ...

I would like to write a Compiled function which is listable only in the first argument, because this allow fast and easy parallelization. How is it possible to do it?
In the following way it does not ...

I am using ListContourPlot to plot a list of points. I am using the PerformanceGoal option inside of ...

I am working on some animations of geographic entities. I have a Manipulate with GeoListPlot as below:
...

in this code cumavg1,cumstd1,giuper1,gilower1 are compiled. however, i dont know how to compile ei and fi to further speed up the calculation. any help will be appreciated.
...

EDIT: Although I have posted an answer based on my current progress, this in incomplete. Please see the "open issues" section in the answer.
Most plotting functions in Mathematica adjust the ...

While watching Stephen Wolfram's twitch stream I saw him use Once for memoization, which surprised me since I thought of Once as ...

- list-manipulation
- matrix
- compile
- plotting
- parallelization
- numerical-integration
- programming
- equation-solving
- mathematical-optimization
- linear-algebra
- functions
- numerics
- differential-equations
- image-processing
- graphs-and-networks
- memory
- code-review
- graphics
- calculus-and-analysis
- manipulate
- dynamic
- function-construction
- sparse-arrays
- import
- evaluation

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