Questions on parallel computing in Mathematica.

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6
votes
3answers
303 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
197 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
91 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
44 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 ...
8
votes
2answers
203 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
68 views

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

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
116 views

Mathematica 10, With and ParallelEvaluate: New syntax?

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

Parallel execution on CPU

i developed following code: ...
5
votes
2answers
200 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
180 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 ...
5
votes
2answers
213 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 ...
2
votes
0answers
86 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 8 ...
5
votes
1answer
304 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 ...
9
votes
1answer
605 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 ...
4
votes
1answer
192 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
143 views

Making ReplaceAll faster

I have a list of functions ncalc that is calculated by ...
4
votes
2answers
146 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
111 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
277 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 ...
19
votes
1answer
249 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
57 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 ...
4
votes
2answers
155 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: ...
2
votes
2answers
283 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
223 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 ...
9
votes
0answers
101 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 ...
1
vote
1answer
129 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
63 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 ...
5
votes
2answers
319 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. ...
4
votes
2answers
158 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
108 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 ...
2
votes
1answer
105 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
16 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
79 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 ...
2
votes
1answer
94 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
60 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
117 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
1answer
152 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
114 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
94 views

Avoid copying memory for each subkernel

Here is a simplified example illustrating my issue; ...
2
votes
1answer
273 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
50 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}] ...
3
votes
1answer
155 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
91 views

Why doesn't my expression evaluate at the subkernel?

Consider this code: ...
2
votes
1answer
146 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 ...
5
votes
1answer
248 views

Definitions are not distributed to parallel kernels

Bug introduced in 10.0 and fixed in 10.0.2. I have a small package with utilities, which looks like that: ...
2
votes
1answer
87 views
1
vote
1answer
94 views

Why does Mathematica Spawn Additional Dock Icons on OS X?

I've been running a calculation in parallel that requires a rasterize, and doing this requires one to wrap the rasterization with a UsingFrontEnd command (as is ...
2
votes
0answers
76 views

What was the thought behind the parallel versions of Table, Map, etc..?

There separately named versions of the parallel analogues of Map[] and friends: ...
2
votes
1answer
125 views

Intensive test parallel computation?

I need an example of a not-too-complicated yet intensive parallel computation in Mathematica. The result of the computation should be known before hand. I need this to test the capabilities of a ...
1
vote
2answers
71 views

Incomplete Parallel Mapping

I am still struggling on how to nicely handle list operations in Mathematica, and perform simultaneously parallel computation. We consider a tab of the form ...