# Questions tagged [julia]

Julia is a high-level dynamic programming language designed to address the requirements of high-performance numerical and scientific computing while also being effective for general purpose programming.

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### Ewald summation in Julia

I am writing a small MD (molecular dynamics) engine in Julia and I noticed that 67% of the time spent running the following Ewald summation function (to calculate coulomb energy of an infinite crystal ...
171 views

### Minimize memory allocations while calculating the matrix representation of a Hamiltonian

I am writing a script using Julia (calling my functions from the REPL) to compute the matrix representation of certain Hamiltonian. After I run my script I see that the memory allocations count is ...
29 views

### Numerical solution to the Lane-Emden equation

I am new to Julia programming, but for fun and practice, I wrote a program that numerically solves the Lane-Emden equation. I even wrote an interactive version that changes the values of ...
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### Non-allocating k-nearest-neighbours between two matrices in Julia

I played around with some optimizations when answering this SO question. Sought is a function which given matrices x of size (m, l) and ...
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### Project Euler #12 in Julia slower than Python?

My code in Julia, almost identical as the Python code (see below), runs in 4.6 s while the Python version runs in 2.4 s. Obviously there is a lot or room for improvement. ...
138 views

### Sort three numbers

So, I wrote this function to sort three numbers in Julia. Any feedback on readability, performance, and Julian-ness would be appreciated. ...
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1 vote
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### How to make my 1D EM algorithm written in Julia faster?

I wrote this code that's supposed to implement a 1-dimensional (!) EM algorithm with k-means initialization: ...
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### Reducing allocations in arbitrary precision calculations with Julia

I am new to Julia and have only written in python before which is most likely also reflected by my coding style. Unfortunately, my applications require very high numerical precision which is why I am ...
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### Fast hamming distance function in Julia that returns a distance matrix

I would like to use Julia to compute the hamming distance on a very large dataset. I need to get back a distance matrix between rows in order to run further ...
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### Discrete event simulation framework for discrete times in Julia

I would like to receive constructive feedback on my simulation framework (this is for my thesis work). I have no formal background in programming, and I am wondering if there is a more effective and ...
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### Parsing values from string into struct using match in Julia

My goal I am parsing from a string which contains token:value pairs into a type. Example: ...
70 views

### Return n largest nonzero entries of an array

For something I'm working on, I need a function that takes in a one-dimensional array vec of integers and returns a boolean array of the same shape indicating where ...
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### Speed of Python vs Julia for Game of Life. Why is Julia slow?

To compare the speed of Julia to Python+numba, I implemented Game of Life in both languages. For anyone who is not familiar with ...
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### Solving 15Puzzle with Julia

Asking here instead of SO as suggested. I'm trying to use Julia to solve the common tile game 15 Puzzle using Julia using A* algorithm. I am quite new to the language and my style may seem very C like....
52 views

### Restructuring loop logic and its effect on allocations

I came across in a code base # TODO this seems very clumsy to duplicate the loop code like this? so I figured I'd give it a shot as a learning exercise. I'd like ...
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### Julia set in Julia (and other fractals)

I've made the following to draw a series of zooming in images of a fractal. ...
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### Sampling and Reconstructing a signal in Julia

I am a newcomer to the Julia world, so I started trying to implement a very simple program: Sample a signal Reconstruct it (various ways, just rectangular for now) Plot it Everything is fine and '...
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### How to speed up simple linear algebra optimization probelm in Julia?

I implemented the LSDD changepoint detection method decribed in [1] in Julia, to see if I could make it faster than the existing python implementation [2], which is based on a grid search that looks ...
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### Optimizing my 2D Ising model code in Julia

I'm just starting to learn Julia, I work primarily in physics and am used to writing most of my code in Fortran90 and occasionally Python for Tensorflow (also Mathematica but that's less relevant). ...
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### Add optional distance range to function

I have a simple brute-force search function: ...
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### Time-series search with early stopping

I want to search for a pattern in a time-series while either ignoring the mean/shift/bias or the scale/standard deviation. Consequently, I've written two functions. The first function searches ...
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1 vote
71 views

### Experience replay memory

I have just begun learning Julia. Here is an implementation of experience replay memory for use in a reinforcement learning algorithm. It is pretty simple, essentially a ring buffer with the following ...
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80 views

### Building an equation [closed]

I've developed a function in the Julia language, using the SymEngine library, which builds an equation. This function works quite quickly, returning a lambdified ...
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1 vote
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### WebSocket based API library in Julia

I made a very bare-bones API "library" in Julia which should abstract the interaction with the API. The API is fairly complex - it's based around 2 core layers an HTTPS/REST API for general ...
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### Bernstein polynomial type for quadratic clipping

I would like to implement a Bernstein polynomial class in Julia for learning purposes. The goal in the end is to implement the quadratic clipping algorithm from this paper. I am completely new to ...
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### For names sake - Project Euler 22

Project Euler - 22 Names scores Using names.txt (right click and 'Save Link/Target As...'), a 46K text file containing over five-thousand first names, begin ...
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### Weighted logistic regression in Julia

I'm trying to estimate a weighted logistic regression as part of a bigger project. I have an implementation in Matlab2015b, but I wanted to give Julia a try to see if I could speed up the estimation ...
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### Parsing simple log files in Julia vs Python

I wrote a log parser in Python and Julia. The Python version takes about 8 seconds to process 350 files, while the Julia version takes about 8 seconds to compile, after which it takes over 20 seconds ...
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1 vote
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### Idiomatic string from/to integer conversions in Julia (Project Euler #33)

I am starting to learn Julia. For getting fluent in the syntax, I am solving some of the easier Project Euler challenges. Problem 33 is about so-called curious fractions, which keep their value after ...
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### Saving the values of all variabled declared in a block

Often when running exprimental code to empirically investigate an algorithm, you tweak a parameter, then rerun the code, and generate a bunch of saved models for various parameters. To make sure I ...
2k views

### Benchmarks of various scientific programming languages for theoretical modelling

For a theoretical modelling course for biology students, I am trying to decide which would be the best technical programming language for doing evolutionary simulations in terms of elegance and ...
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### Speeding up OpenCL matrix-vector multiplication

So I'd like to get a performance boost above and beyond standard Julia matrix-vector multiply, using my Intel HD Graphics 4000 1536 MB GPU, but I can't do better than an order of magnitude worse ...
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### Recursively walk directories with a callback function

This code works, but I want to refine it: ...
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1 vote
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### Using RemoteChannels for an parallel iterable map

RemoteChannels hit with julia v0.5 There are no examples online, but I managed to get them to work. They are still very new, and all this whole area of multithreading code continues to have running ...
1k views

### Sort Algorithms in Julia

Similar to this question here, I am trying to implement sort algorithms in Julia, as part of a package. The code for the implementation is as follows: ...
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### Search algorithms in julia

I've been trying to implement the basic search algorithms: Sequential search for ordered and unordered arrays and the binary search algorithms, as part of a package. So, this is the implementation: <...
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### Computing the double Integral using MonteCarlo techniques using Julia

I decided to try and learn Julia for doing scientific computing, and I decided to tackle the problem of finding $$\int_{D_{\frac{1}{4}}} x^4 + y^2 dA$$ where $D_{\frac{1}{4}}$ is the part of ...
158 views

### Implementing cat function in Julia

I wanted to implement the cat function in Julia and I ran a few test cases but I am not sure if I am missing anything: ...
1 vote
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### Flattening lists of Vectors and Matrices into arrays

For many optimisation methods the parameters must be given as a single vector, such as Optim.jl. But for many interesting functions the parameters/coeffients to be optimised are matrices, or a mixture ...
178 views

### Latent Dirichlet Allocation Posterior Inference

I have implemented Latent Dirichlet Allocation in Julia. Since the code is rather long, I copied the essential part here but the complete code can be found on GitHub. ...
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### Kernel density regression in Julia

Here is a naive implementation of a kernel density regression algorithm in Julia. The code works, but there is quite a bit of room for improvement though. First, there is not an optimal bandwidth ...
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### Iterative procedure to get 3D coordinates from distance constraints

Imagine you have a series of n points randomly generated in a box in 3D space. You also have a list of distance bounds, e.g. points 5 and 3 should be between 1.0 and 2.0 Angstroms apart. There are ...
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### Terry Feagin's 10th order explicit Runge-Kutta method

The following Julia code implements Terry Feagin's 10th order explicit Runge-Kutta method (a more accurate cousin of RK4). Though the structure of the code is quite simple (i.e. no cyclomatic ...
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731 views

### Functions for outputting the rows and columns of a matrix

I often want to iterate either row-wise or column-wise though a matrix in Julia, so I've created a pair of functions to help: ...
224 views

### Individuals reproduce and mutate

How can I improve the performance (in terms of computation time) of this code? ...
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### Julia RPN calculator algorithm ported from Python version

I've just finished the Reverse Polish Notation task in Julia from rosettacode.com by porting the existing Python code. There are only a few lines I don't get how to port: ...
376 views

### Neural Network in Julia

I am currently trying to implement a Neural Net in Julia with the goal of eventually implementing a stacked autoencoder. My code seems to work but I would appreciate any constructive criticism. If ...
245 views

### Speed optimization for girth-counting algorithm

I have the following girth-counting algorithm on a large 0-1 matrix and I need to optimize it for speed: ...
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