156k views

Where can I find examples of good Mathematica programming practice?

I consider myself a pretty good Mathematica programmer, but I'm always looking out for ways to either improve my way of doing things in Mathematica, or to see if there's something nifty that I haven't ...
5k views

Why won't Parallelize speed up my code?

What reasons are there that can cause parallelized Mathematica code not to run with full performance?
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1k views

This time I have a very short question. Is there a deeper reason why ParallelMapThread does not exist? Regards, Frink
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4k views

Why is ParallelTable slower than Table?

Update Following a comment of Szabolcs have changed Timing to AbsoluteTiming. The results are virtually the same. Original post I have accidentally observed the following surprising result. So, why ...
839 views

Why is this parallel evaluation with Dispatch[] so slow?

Can you efficiently parallelize this? The parallel versions are much slower than the sequential version, and I'm not sure why. Does SetSharedVariable allow ...
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937 views

ParallelMap vs Map performance comparsion

The ParallelMap claims doing map faster than the normal Map, and I checked the demo does as the document describing but, I try ...
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1k views

Most efficient way to obtain samples from high-dimensional multivariate distributions?

Is MultinormalDistribution[] efficient and easy to use for high dimensions? I have a variable $n$ representing the dimension of a Monte Carlo integration I do on a ...
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576 views

Fastest way to test if a numerical array has complex elements

I am looking for the fastest way to test whether an n-dimensional numerical (NumericQ) array (in the ArrayQ sense) is complex or ...
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3k views

Why is parallel slower?

I always assumed that distributing a computation is faster, but it isn't necessarily true. When I do Sum[i,{i,10^4}] I retrieve an answer much faster then if I do <...
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423 views

Parallelization of distinct array write access from subkernels

I'm working on an implementation of a multivariate FFT, which is (or at least should be) highly parallelizable due to the row-column-algorithm. However, i can't figure out how to implement that. The ...
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579 views

Making Monte Carlo simulation with ParallelTable

I would like to to MonteCarlo simulations of various regressions - basically, doing OLS under various conditions to test approaches. On my macpro 2x 2.8 GHz quad core Xeon, 32 Gb RAM DDR2 @ 667 Mhz, ...
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724 views

How can I speed up image importing? [closed]

The following examples show how slow it is to load a simple GIF. Can anything be done to make it faster? System #1: Mathematica 8.0.1.0, HP notebook, Win7 64Bit, 2 x 2.4Ghz Intel Core i5, 2GB RAM, w/ ...
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1 vote
1k views

ParallelTable 70 times slower on 16 cores than Table on single core

Consider these code(sorry it's messy), why the ParallelTable version is 70 times slower than the Table version? ...
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512 views

Why I only get 2X speedup when parallelized with 16 kernels

I'm trying to parallelize a function by ParallelTable, and it seems the speedup is not very good. I have 16 parallel kernels on my computer node: ...
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