Questions on parallel computing in Mathematica.

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3
votes
1answer
420 views

Determining the partitioning of Do loop iterations between kernels?

Say I have some Do loop that I'd like to evaluate in parallel: Do[Something, {i, 1, M}]. I'd like to split this list up into ...
3
votes
1answer
43 views

Shared variable can not be distributed again after UnsetShared

I see a weired behavior in my MM 10.3 version. Can someone reproduce it or explain what is going on? The code is easy: ...
3
votes
1answer
104 views

Why is $ProcessorCount not equal to LaunchKernels[ ]?

Normally, number of $ProcessorCount should be the same as LaunchKernels[], but if they are not the same, what is the problem? ...
3
votes
1answer
83 views

Why doesn't my expression evaluate at the subkernel?

Consider this code: ...
3
votes
1answer
273 views

Issue in ParallelTable after evaluating another function using NDSolve and FindRoot. What is wrong with this inverse?

I am trying to find the inverse of a function which is defined through NDSolve and NIntegrate. The question is pretty similar ...
3
votes
1answer
99 views

Creating a parallelizable DiscretePlot

To my knowledge, DiscretePlot cannot be parallelized, although one can simulate the default behavior of DiscretePlot and get the ...
3
votes
2answers
192 views

Definitions inside ParallelTable?

How can I make definitions inside ParallelTable to use them outside? For example, if I execute: ...
3
votes
1answer
86 views

local logfiles for remote kernels

I'd like remote slave kernels to produce log files on my local machine, subject to the following constraints: 1) I don't want to install a distributed filesystem or do other administrative work on ...
3
votes
1answer
168 views

Image background subtraction using parallel computing

I am developing a program for pattern recognition. I want to use the parallel computing to get a real time application. I have two cameras where each one gives n frames/second. I need to process the ...
3
votes
1answer
286 views

Parallel kernel and front end

I have a piece of code which looks like this: ParallelTable[ Monitor[ Table[ <code here> ,{i,i1,i2]; ,i]; ] so basically a ...
3
votes
1answer
91 views

ParallelTable Works in Regular Notebook but Gives Error When Packaged

Consider the following: ...
3
votes
1answer
645 views

Are there any openCL test suites?

I have a new ATI gpu that I have been trying on 3 different distributed computing projects. I get errors on each work unit. The errors indicate No Protocol which could be caused by a bad environment ...
3
votes
1answer
47 views

LaunchKernels behavior

I have one processor with 2 cores on my local computer. CloseKernels[];LaunchKernels[] (* {"KernelObject"[1, "local"], "KernelObject"[2, "local"]} *) I can't ...
3
votes
2answers
101 views

Add Results of ParallelMap in Parallel

I'm new to coding in parallel, but I really could use it. I need a command to call a function on each element in a huge list, and then add them all up. Currently I use something like this: ...
3
votes
1answer
184 views

Setting up parallel remote kernels

I'm having trouble setting-up a parallel remote kernel. I have correctly set-up remote kernels and can use them instead of the local kernels, by executing tunnel.sh ...
3
votes
1answer
140 views

Parallel Apply on a deeply nested expression

I have a deeply nested expression, i.e. something like {{{{...}..}..}..}, and I'd like to use Apply in a parallel fashion, e.g. ...
3
votes
1answer
86 views

Dynamic Output during ParallelMap

I can't seem to figure out how to dynamically output a variable that is being used in a parallel evaluation. Below is an example function that demonstrates my problem. ...
3
votes
1answer
146 views

Using ParallelMap to run multiple Game of Life simulations simultaniously

My Assignment and Code As an exercise in Parallel computing I've been tasked with implementing Conway's GoL in a way such that at every iteration only a fraction of cells are updated. I'm then to run ...
3
votes
1answer
613 views

Parallel evaluation and memory use

I have never used Mathematica's parallel evaluation before and have some trouble getting it to work properly. For the record, I am running Mathematica 9 on Linux with an Intel Core i7 processor (4 ...
3
votes
1answer
185 views

How do I fix Needs[“OpenCLLink`”] failure?

In Mathematica 8.0.4 under Mac OS X 10.8.2, when I evaluate Needs["OpenCLLink`"] I get error ...
3
votes
0answers
38 views

Why is a LibraryLink function, which returns a list, not parallelizing with ParallelTable?

First example: librarylink function return a list of two element ...
3
votes
0answers
73 views

Export bug in combination with ParallelTable?

I am programming with Mathematica 10.3.1.0 on Windows 10 Professional 64 Bit and have an i7-4940-MX 3,1 GHz processor (4 cores). When I use in the example code below ...
3
votes
0answers
68 views

Improving the speed of an optimization algorithm via compilation and parallellization

I have written an implementation of eight variants of the PSO-algorithm and I want to test them over a set of test functions. I am using parallelization as it improves the speed a lot and I have also, ...
3
votes
0answers
119 views

Parallel Kernels and Hyperthreading

I am using Eigenvalues a large number of times on a machine with 8 cores. When I run Eigenvalues one time without any parallel ...
3
votes
0answers
91 views

How to speed up summing a large number of vectors

First let me explain what I am trying to do in my code. Assume that I send a very short chirp (2,000 ms long) into a domain filled with 20,000 particles randomly scattered in the domain. The ...
3
votes
0answers
94 views

AppendTo or Part in a ParallelDo?

I have a question regarding how memory is managed in parallel. Specifically, I'd like to know what is the better practice when constructing an array within a ...
3
votes
0answers
103 views

Launching 49+ local kernels fails in 10.0.2 [closed]

I do large-ish parallel computations in Mathematica on quad socket 16 core nodes (64 physical cores). In version 8.x, LaunchKernels[64] works reliably. In version 10.0.2, LaunchKernels[48] works ...
3
votes
0answers
53 views

Parallelization and memoization? [duplicate]

I have an expensive function on discrete values, f[n_] := f[n] = n^2 (* Expensive calculation *) Since f[n] is an expensive ...
3
votes
0answers
80 views

k-means clustering in parallel

How can the k-means algorithm for some given distance function be implemented using ParallelMap or other parallel processing program constructs in Mathematica?
3
votes
0answers
295 views

Death of parallel sub-kernels

EDIT : Finally, the new Mathematica 10.0 seems to fix it. I have a little parallelization problem. I wrote a code to generate a quasicrystal by dynamical generation. Here the code: ...
3
votes
0answers
106 views

LibraryLink parallel performance

I'm trying to use a LibraryLink function in parallel. It is an embarrassingly parallel problem, so that no dependency between those parallel tasks. However I can only get the parallel efficiency about ...
3
votes
0answers
470 views

Remote kernel shuts down after several seconds

I have Mathematica 9 installed on two Windows Server 2008 R2 machines. Now i want to try using one of them as a frontend with local kernels and the other one for remote kernels. OpenSSH 6.5 for ...
3
votes
0answers
206 views

Launching Remote Kernels takes a lot of time

I recently played around with establishing a remote kernel setup without using mathematica grid. To do this I use the LaunchKernels[] command and ...
3
votes
0answers
226 views

Mathlink and multithreading

In order to make my computations faster I have developed a C/C++ application calling Mathematica kernel and performing many operations using Mathematica functions for equation solving. Now I want to ...
2
votes
1answer
737 views

3 hour calculation? ParallelMap & ParallelTable

I'm having some problems with slow Mathematica code... I'm basically doing a computation that's is expected to take 3 hours (!) in my Core i7 with 4 processors... I'm basically computing an index (of ...
2
votes
2answers
695 views

Difference between sub MathKernel and MathKernel

When I try to run Mathematica processes in parallel on a Linux based server, I see that my server allows 7 MathKernels and 28 sub MathKernels. I was wondering what the difference is and how I can take ...
2
votes
2answers
234 views

Follow each pixel brightness in set of images (Memory constrained)

I have a set of 2700 consecutive png images (8bit, 2048*2048 pixels). I would like to visualize the intensity variation of each pixel vs. image number. Here is an example of 10 images: ...
2
votes
1answer
246 views

Parallelization of REvaluate[]?

Is there a way to run several RLink computations via REvaluate[] in parallel, e.g. with ParallelTable[]?
2
votes
1answer
574 views

Suppress warnings in ParallelTable

I'm using ParallelTable to evaluate a function that involves NIntegrate. There are a lot of ...
2
votes
2answers
57 views

Disappearing variable in parallel computations

I have a problem with parallel computations. When I try to evaluate formula like this: Do[m[i]=2,{i,1,10}] and then I try to call for instance ...
2
votes
2answers
360 views

Is there a way to parallelize the convolution component of EdgeDetect?

Provided an image like - test = Import["http://upload.wikimedia.org/wikipedia/commons/d/d5/Sunflowers.jpg"] We can run ...
2
votes
1answer
280 views

Mathematica 7: Problems when evaluating Fourier inside a ParallelTable

after I got such a great response for my first question on this site, I'm very encouraged to asked my second one! So here it is, very generally: To speed up a "row-wise" (i.e. 1D) operation on a ...
2
votes
1answer
307 views

Clearing distributed definitions from remote kernels

The documentation shows the following example to "Remove a distributed definition..." Oh, course this doesn't work without redefining the function prior to re distributing the definition. The ...
2
votes
1answer
127 views

ParallelEvaluate: Evaluation Rules and Increment

I'm trying to understand how ParallelEvaluate works, considering the two following snippets: ...
2
votes
1answer
187 views

Understanding a slowdown associated with wrapping a set of nested Do loops with a ParallelDo expression

I have a set of set of nested Do loops that require data from three different arrays (though the position from each array is fixed per cycle of the outer Do loop). Let's call these arrays: ListA, ...
2
votes
1answer
102 views

How can I set the kernel for CreatePalette?

I have written some code that requests some calculations from an SQL server every N seconds and uses a palette: CreatePalette[Dynamic[DateListPlot[...]]] I ...
2
votes
1answer
398 views

Light Weight Grid and core limitation

I am trying to figure out what would be best for running some simulations using multiple computers where each has it's own mma 8 licence. The main part of the computation involves a parallelized table ...
2
votes
1answer
71 views

Parallel kernels cannot launch: LinkOpen::linke error [closed]

I have been regularly using parallel kernels on my machine but this morning all I receive is a cryptic error whenever I call any parallel function (LinkOpen::linke). As far as I can see sequential ...
2
votes
1answer
87 views
2
votes
1answer
127 views

ParallelTable slowdown for a task involving ComponentMeasurements

I'm having trouble understanding a slowdown associated with code I'm running, which should be trivial to parallelize. My code looks something like this: ...