nbody | Fast n-body gravitational simulation code

 by   fding C++ Version: Current License: No License

kandi X-RAY | nbody Summary

kandi X-RAY | nbody Summary

nbody is a C++ library typically used in Simulation applications. nbody has no bugs, it has no vulnerabilities and it has low support. You can download it from GitHub.

Fast n-body gravitational simulation code, written in C++ with ports to other slower languages. Currently supported languages: C++, Python.
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              nbody has a low active ecosystem.
              It has 16 star(s) with 6 fork(s). There are 4 watchers for this library.
              OutlinedDot
              It had no major release in the last 6 months.
              There are 5 open issues and 0 have been closed. There are 2 open pull requests and 0 closed requests.
              It has a neutral sentiment in the developer community.
              The latest version of nbody is current.

            kandi-Quality Quality

              nbody has no bugs reported.

            kandi-Security Security

              nbody has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.

            kandi-License License

              nbody does not have a standard license declared.
              Check the repository for any license declaration and review the terms closely.
              OutlinedDot
              Without a license, all rights are reserved, and you cannot use the library in your applications.

            kandi-Reuse Reuse

              nbody releases are not available. You will need to build from source code and install.
              Installation instructions are not available. Examples and code snippets are available.

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            nbody Key Features

            No Key Features are available at this moment for nbody.

            nbody Examples and Code Snippets

            No Code Snippets are available at this moment for nbody.

            Community Discussions

            QUESTION

            Python code repeating n+1 times every run
            Asked 2021-May-11 at 00:39

            I've been working on an application which contains a small, simple http server to handle post requests on occasion. The server and all functionality around it works fine, but each time the server runs, log output would tell me that my code is being run multiple times, plus one time for each request the http server handles.

            ...

            ANSWER

            Answered 2021-May-11 at 00:39

            It turns out that this wasn't an issue with my code, but rather an issue with the logger I was using which was adding multiple console handlers for the same logger, causing output to be repeated. I fixed this in my cli library.

            Source https://stackoverflow.com/questions/67446370

            QUESTION

            Updates to elements of list are applied to the whole list python
            Asked 2021-Mar-16 at 15:32

            I am trying to write just a simple program to simulate an N-Body system using python (and pygame for GUI just because I have more experience than tk). The issue I am running into is I made a body class that is a subclass from a sprite. I have an adaptable list size of n that appends that many bodies into the list. To start I just decided to have updates be performed in a double for loop with a final for loop that passes the updates after they have been calculated (I know this is not efficient, not the point). My issue is that when I pass an update to an element of this list, the update is applied to every thing in that list. What is going on here? Why are these completely separate elements tied together? Necessary code below

            Body class

            ...

            ANSWER

            Answered 2021-Mar-16 at 15:32

            See Class and Instance Variables:

            Generally speaking, instance variables are for data unique to each instance and class variables are for attributes and methods shared by all instances of the class.

            Since val and acc are class attributes they are shared by all Body objects and as you mentioned in your question: "these completely separate elements tied together".

            vel and acc have to be instance attribute instead of class attributes:

            Source https://stackoverflow.com/questions/66658256

            QUESTION

            NBody problem parallelization gives different results for the same input
            Asked 2021-Feb-04 at 06:09

            This an MPI version of the NBody problem. I already have an OpenMP version and its results are the same as the nbody version with one thread, but the MPI results differ, above all at the last interactions. At the first interactions, the outputs are quite similar but at the end, the outputs differ a lot.

            ...

            ANSWER

            Answered 2021-Feb-03 at 19:48

            You get different results because your algorithm is solving a completely different problem when running with more than one MPI rank.

            You are performing domain decomposition by splitting the array of particles in parts, and then each rank computes the forces only taking into account the particles in its own subdomain:

            Source https://stackoverflow.com/questions/66031181

            QUESTION

            How to parallelize access to a class?
            Asked 2021-Jan-28 at 03:14

            I've implemented a simple direct Nbody simulation in python. I'm looking to parallelize it as we are doing the same operation again and again. In C++, I would have use openmp, but python doesn't have it.

            So I was thinking to use the multiprocessing module. From what I understand, I would need a manager to manage the class (and the list particles?) and I was thinking of using a starmap pool.

            I'm quite lost on how to use these function to achieve any semblance of parallelization, so any help is appreciated.

            PS: I'm open to use other module too, the easier the better. The class is ditchable if using numpy array (for position velocity mass) solves the problem, I'll go with it.

            Code:

            ...

            ANSWER

            Answered 2021-Jan-28 at 03:14

            If you want to share a list of custom objects (such as particle in the question) among processes, you can consider a simplified example here:

            Source https://stackoverflow.com/questions/65929422

            QUESTION

            Dart/Flutter - How to get second since epoch : Twitter API error code 135 ( Timestamp out of bounds)
            Asked 2021-Jan-13 at 15:12

            Hello I hope you are well. Recently, I have a problem using the Twitter API precisely at the time of publishing a tweet. According to the documentation here, my request must contain in its header a field oauth_timestamp which is the number of seconds since the epoch(seconds since the Unix epoch).

            With Dart(Flutter) I retrieve the number of milliseconds elapsed since the epoch which I then divide by 1000 to obtain this value in seconds. Ex:

            ...

            ANSWER

            Answered 2021-Jan-13 at 15:12

            I solved the problems that prevented me from publishing a tweet using the Twitter API.

            First of all: I kept my way of retrieving elapsed time (in seconds) since epoch

            Source https://stackoverflow.com/questions/65702681

            QUESTION

            XmlService getChild doesn't return named Element
            Asked 2021-Jan-08 at 13:47

            For some unknown reason, I can't make getChild work for a nested element. Here's my sample Apps Script Code:

            ...

            ANSWER

            Answered 2021-Jan-08 at 13:47

            The element you want has a different namespace than the root.

            Source https://stackoverflow.com/questions/65629110

            QUESTION

            request.POST not reading form data in django
            Asked 2020-Oct-29 at 06:02

            I have my views file:

            ...

            ANSWER

            Answered 2020-Oct-29 at 06:02

            A MultiValueDictKeyError comes when you try to access something from request.POST which doesn't exist. It's basically the same the python KeyError. Use request.POST.get('key', 'default_if_key_doesn't exist')

            Source https://stackoverflow.com/questions/64585631

            QUESTION

            could not select device driver "" with capabilities: [[gpu]]
            Asked 2020-Sep-24 at 17:06

            I am trying install Cuda on WSL 2. I am following instructions such as this.

            After executing every step, I try to check if gpu is available in the Linux environment by executing docker run --gpus all nvcr.io/nvidia/k8s/cuda-sample:nbody nbody -gpu -benchmark (as suggested by the aforementioned instructions).

            But I get the following error: docker: Error response from daemon: could not select device driver "" with capabilities: [[gpu]]. ERRO[0000] error waiting for container: context canceled.

            Any ideas what might be the cause of this?

            ...

            ANSWER

            Answered 2020-Jun-20 at 10:20

            I was having the same issue. Are you using Docker Desktop for Windows? Because I was, and I found out that WSL2 + CUDA does not work with Docker Desktop for Windows:

            https://forums.developer.nvidia.com/t/hiccups-setting-up-wsl2-cuda/128641

            Instead, install Docker manually in WSL2 (as is suggested in the tutorial you linked):

            Source https://stackoverflow.com/questions/62477330

            QUESTION

            Java is not taking user input for the first variable
            Asked 2020-Sep-10 at 10:03
            import java.util.Scanner;
            
            public class NoteIt {
                public static void main(String[]args) {
            
                    Scanner s = new Scanner(System.in);
                    int Answer;
                    int i=2;
            
                    System.out.print("\nPlease Enter your Name: ");
                    String Name = s.nextLine();
                    System.out.println("Welcome to Note-It "+Name+", We hope you'll enjoy our application. ");
            
                    String[][] Main = new String[2][2];
            
                    Main[0][0]="Create new Note";
                    Main[1][0]="View My Notes";
            
                    System.out.println("\nPlease select what to do: \n");
            
                    for(int n=0; n<2; n++){
                        System.out.println((n+1)+") "+Main[n][0]);
                    }
                    System.out.print("\nPlease enter your response: ");
                    Answer = s.nextInt();
            
                    if(Answer == 1){
                        i++;
                        Main = new String[i][2];
                        System.out.print("\nTitle: ");
                        Main[i-1][0]=s.nextLine();
                        System.out.print("\nBody: ");
                        Main[i-1][1]=s.nextLine();
                    }
            
                }
            }
            
            ...

            ANSWER

            Answered 2020-Sep-10 at 10:03

            According to @Rohit Jain, That's because the Scanner.nextInt method does not read the newline character in your input created by hitting "Enter," and so the call to Scanner.nextLine returns after reading that newline.

            Description here: check this question too

            Try this it may help...

            Source https://stackoverflow.com/questions/63826735

            QUESTION

            Is there a better way for python post server to handle different file types?
            Asked 2020-Aug-04 at 04:28

            I have a post server written in python3.6.9, running on the localhost behind an apache2 reverse proxy. It receives a base64 file uploaded via Powershell and decodes them. Text Files get saved to the directory ./Public/example.txt. If bytes are uploaded, it handles the error with 'except binascii.Error' and I can properly write it to the directory. Both file types saved this way do so by taking the URI and replacing '/store.json' with nothing. If no FileName is present in post data, an 'except IOError' will write it to ./store.json in the current directory.

            Here is the main code:

            ...

            ANSWER

            Answered 2020-Aug-04 at 04:28

            First off welcome to SO.

            So a few things that may help you out. People don't usually use python's HTTPServer unless you're wanting to control the lower part of http request and response. If you want to use a easy to use/setup http server flask is a great option as it will handle parsing POST data as well as saving files when they come through.

            Q1. Is there a better way to identity files?

            A1. This depends. During an http request to upload a file http standard is to upload the file name and extension along with the file's bytes. If you only upload bytes then most http servers will just ignore it and return an error. So if you send the name and extension along with the bytes than you know what kind of data it is and how to store it.

            Also base64 is an encoding. So the only way to know if the encoding is good or not (malformed/dropped bytes) is to actually try and decode it and then catch any errors when it finds them. There is no way of asking it if it's a valid encoding without it actually trying to decode the data.

            Q2. Can you blindly handle errors in python?

            A2. Yes you can though it is discouraged to do so.

            Source https://stackoverflow.com/questions/63233854

            Community Discussions, Code Snippets contain sources that include Stack Exchange Network

            Vulnerabilities

            No vulnerabilities reported

            Install nbody

            You can download it from GitHub.

            Support

            Yeah, this version of the code probably has a few bugs, and the interface with Python is rather ugly. I plan to:. Add support for other time formats in returning the Solar System. Save initial conditions for the solar system at other times to allow faster computation. Add more objects into the solar system. Compile binaries for Linux and Macs. Fix any bugs that may come up.
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            https://github.com/fding/nbody.git

          • CLI

            gh repo clone fding/nbody

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            git@github.com:fding/nbody.git

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