Questions on parallel computing in Mathematica.

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3
votes
0answers
48 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 ...
5
votes
3answers
187 views

Parallel and non-Parallel functions return different results?

A friend of mine observed that when running ParallelMap or ParallelTable that he would get different results than when running ...
3
votes
1answer
179 views

How can I understand this short example?

First launch kernels LaunchKernels[4] {KernelObject[5, "local"], KernelObject[6, "local"], KernelObject[7, "local"], KernelObject[8, "local"]} Then I calculate ...
2
votes
0answers
50 views

Is it possible to automatically apply Parallelize when possible

Parallelize in Mathematica is pretty easy to use. Most of the time, applying Parallelize to an expression, it tries to evaluates ...
1
vote
0answers
32 views

Inconsistent font rendering when using a remote kernel on a different OS

I have a Mathematica 10.0 on Linux and one on OSX. I'm using the OSX as a remote kernel. During parallel computation, if I render some graphics, the fonts and axes are not rendered the same way ...
7
votes
2answers
112 views

How to write a custom ParallelTable command that monitors progress automatically

I am using a lot of ParallelTable and want to avoid wrapping it in a Monitor call each time. Since each of the calls inside ParallelTable will already consume considerable time, I do not mind the ...
2
votes
0answers
38 views

Export on local machine results of a parallel computation using remote kernels

I've got a long calculus to do with Mathematica. I've Parallelized the code using local kernels and remote kernels. I'm using a ParallelDo loop with an ...
3
votes
1answer
74 views

Mathematica 10, With and ParallelEvaluate: New syntax?

Consider the following trivial code to evaluate something on a parallel kernel ...
1
vote
1answer
81 views

Parallel execution on CPU

i developed following code: ...
4
votes
2answers
93 views

Why doesn't ParallelTable work on this very simple example?

For some reason, I'd like to use ParallelTable with a variable number of iterators. Table[a[1], {a[1], 0, 10}] works fine: ...
0
votes
1answer
125 views

ParallelTable slower than Table in the presence of an Association?

So after testing some things I am completely reformulating my problem. First an example ...
3
votes
2answers
147 views

ParallelMemberQ

I tried to make a parallel version of MemberQ for use with a large list, but failed miserably in terms of performance. I used Partition to subdivide the list and ParallelMap to perform the MemberQ ...
1
vote
0answers
37 views

How many kernels to set based on CPU?

Looks like 4 kernels are enough? My CPU is i7 4790K as given here. Does it also depend on the tasks and the codes? My understanding is that regardless what the benchmark says, I could always use ...
5
votes
1answer
115 views

Reap, Sow with Parallelize: bad performance, why?

I have a question about the performance of Reap and Sow with Parallelize. I am aware of the following questions How to collect result continuously (interruptible calculation) when running parallel ...
6
votes
1answer
201 views

Does Mathematica take advantage of hyper-threading (if it is available)?

I do not know much about computer architecture, but some Intel processors have hyper-threading technology, which can apparently improve parallelization for applications that take advantage of it. In ...
3
votes
1answer
160 views

How to further accelerate arithmetic with Fermat Pseudoprime and Fibonacci number

I've been working on this all night, and I have made this go pretty fast, compared to my first iteration of the program, but now I'm out of ideas. I'm trying to write a program to test (by good ...
1
vote
1answer
129 views

Making ReplaceAll faster

I have a list of functions ncalc that is calculated by ...
3
votes
1answer
58 views

Running bits of code in a separate kernel

I am using Mathematica to generate 3D graphics frame for a video. The process goes as follows: Loop over a counter i Use ...
0
votes
0answers
36 views

Can LinearSolve use Parallelize and WorkingPrecision in computation

I am looking for a two things while calculating the large array matrix equation: 1) To increase the precision in simple LinearSolve[] function 2) To find a way to parallelize the computation on all ...
3
votes
1answer
87 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 ...
14
votes
1answer
163 views

Two, maybe related, issues with ParallelTable

I will use a very simple example for demonstrating two issues I face with ParallelTable, one with respect to the speed and one with respect to the use of memory. These issues might be related. Let us ...
2
votes
0answers
28 views

ParallelSubmit and WaitNext: check if a job is done before calling WaitNext

Say I process something with ParallelSubmit: LaunchKernels[] job = ParallelSubmit[1 + 2] Parallel`Developer`QueueRun[] Then, I will use ...
3
votes
2answers
101 views

Assignments in ParallelDo when using indexed variables

For convenience I use an indexed variables syntax to hold results of long computations for different integer parameters: ...
0
votes
0answers
25 views

Generating a list consisting of function values like in a triangular matrix

A goal is to generate a SymmetrizedArray of dimension n^k with specified symmetry (let it to be ...
0
votes
0answers
42 views

What is the right way to combine a Package, Module, ParallelTable and NIntegrate?

I am stuck with a curious problem. I would like to to have a package from which i can call a function test[path], which then performs a time consuming numerical ...
1
vote
2answers
72 views

Limit the number of processors used by ParallelTable?

By default, ParallelTable will use all the processors available in a PC. Is there a way to set a limit to the number of processors used by ...
0
votes
2answers
106 views

Numerical 3D Integration in Mathematica [closed]

My question in short is: Is it possible to make numerical 3D integration in mathematica efficiently? Or am I gonna have to move this to C++? I feel this problem is way too trivial to go to C++, so ...
3
votes
0answers
52 views

Smart use of ParallelMap over Plus

I'm looking for ways to speed up calculation of a integral with a many-terms integrant. The obvious way is to go in parallel. I was surprised, but for some tests integration by ...
0
votes
0answers
44 views

Parallel calculation with SetOptions

Is it possible to distribute the effect of SetOptions to parallel kernels? Here is how I encountered the problem: I am trying to calculate a lot of numerical ...
1
vote
1answer
91 views

DSolve for a huge linear inhomogeneous ODE in parallel

I have a linear inhomogeneous ODE with constant coefficients, which I need to solve symbolically. The problem is that the inhomogeneity is sum of more than 100 terms (however, each term itself is ...
0
votes
2answers
45 views

Parallel evaluation hangs before doing anything

[I use Mathematica 9.0.1.0 on OS X Yosemite 10.10.2.] I am experiencing difficulty with parallel evaluation that I am finding extremely perplexing to troubleshoot. I define the following function in ...
4
votes
2answers
184 views

NDSolve in Mathematica won't use all the cores avaiable

When I solve a system of differential equations in Matlab, the task manager shows that all the CPU cores are in use. This is not true when I solve the same system in Mathematica. I have six cores. ...
0
votes
0answers
40 views

Parallelize: No speed-up when using with FindMaximum

I have developed a program to compute the maximum value of an specific function multiple times, with different parameter values each time. I've been using the ...
4
votes
2answers
117 views

Using Throw within ParallelDo

I've noticed that I can't Throw from within a ParallelDo in the same way that I can from inside Do. For instance, the following will work as anticipated with Do but not with ParallelDo: ...
1
vote
0answers
54 views

ParallelMap not using all of the available kernels

Please note: I cannot provide the code here, since the project is far too big to post at any Internet forum. I have a computer with eight logical cores. I have Mathematica Version 10.0.2, and I am ...
1
vote
1answer
70 views

ParallelMap doesn't work with an Association. Is this a bug?

I receive a ParallelCombine::nopar1 error when executing ParallelMap[Identity, <|1 -> 1, 2 -> 2|>] Is this an ...
1
vote
0answers
15 views

SetSharedVariable on multi-dimensional array [duplicate]

I am trying to modify a multidimensional array inside a ParallelDo, but I get the error 'Symbol array is Protected'. How can I solve it? I attach here a minimal code to reproduce the error: ...
1
vote
1answer
47 views

Break out of ParallelDo

In a parallelised computation, I would like each kernel separately to break out of ParallelDo when it has finished going through the loop once. For a single kernel ...
1
vote
1answer
53 views

Changing a Part of a variable within ParallelDo

I want to evaluate nested do as a parallel computations. My formula looks like: ...
2
votes
2answers
54 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 ...
3
votes
0answers
71 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 ...
0
votes
0answers
33 views

Side effects in ParallelDo

I am trying to import many different matrices saved as separate .MX files in one bix matrix. When I used ...
3
votes
1answer
117 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. ...
2
votes
1answer
51 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. ...
1
vote
0answers
81 views

Avoid copying memory for each subkernel

Here is a simplified example illustrating my issue; ...
0
votes
1answer
98 views

Appending elements to a list in parallel table

Is there any way to store values in a list that is being computed in parallel? For example, if ParallelTable is computing some ...
0
votes
1answer
42 views

How to set a shared variable Power (a modified one)?

Unprotect[Power]; Power[0|0., 0|0.] = 1 ; Protect[Power]; Table[0^0, {i, 5}] No problem at all. ParallelTable[0^0, {i, 5}] ...
2
votes
1answer
75 views

Problem with ParallelTable

The following code creates an array of length N, such that the sum of elements is less than or equal to p and each element is between 0 and l. All elements are integers. (code courtesy, Kellen Myers ...
3
votes
1answer
70 views

Why doesn't my expression evaluate at the subkernel?

Consider this code: ...
2
votes
1answer
81 views

How to access directly the “CUDA Memory” address from another parallel kernel?

I work with CUDALink and have some small successes. I use direct calculation on GPU without using CPU (only for sanding commands for CUDA function). Until now I have stored on the hard drive with ...