For loop is taking too muc time to execute

[altenbach]

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@GerdW wrote:

Loopless:

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Have you counted the allocation dots? Probably significantly more memory overhead with all these seperate intermediary arrays (2D, 1D). Not sure if a few ms are worth it...

[GerdW]

Hi Christian,

that's the usual trade-off: time vs. memory consumption…

(I wondered it's even faster when allocating more array wires in between.)

[altenbach · Accepted solution]

Curiously, interlacing is faster than my typecasting (~19ms , or about 8ms when the loop is parallelized).

I am sure we can squeeze a little bit more out of it, but going from 5 minutes to 10ms is quite good, IMHO ;))

The first estimate of getting 1000x improvement was low. We got about 30000x! 😮

[GerdW · Accepted solution]

Hi,

not getting so much faster, but there also is a DecimateArray for each InterleaveArray:

Atleast it fits the postage stamp… 😄

[altenbach · Accepted solution]

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@crossrulz wrote:

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Preallocating the array and not reshaping seems to help quite a bit. 

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It surprised me that the concatenating tunnel is about 20x slower, even though the compiler could probably figure exactly what to do based on the build array with two scalars inside the loop.

Here's what I probably would do in the end:

[altenbach · Accepted solution]

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@GerdW wrote:

A tleast it fits the postage stamp… 😄

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No kidding 😄