For loop taking way too long to execute

[Smdx]

Hello fellow LabVIEW users

I have encountered huge problem that following for loop takes way too long to execute, I need to run two same for loops like the following one and they both together take horribly long time - 18 seconds on average. Surprisingly, when I combined both loops it took even longer.

For loop above is doing (or should do) following part of code:

for i = 1 : 11850
    signalAvr(i) = signal(i);
    for j = 1 : 149                 
        signalAvr(i) = signalAvr(i) + signal(i + j);
    end
end    

Is there any way of speeding up this loop? What am I doing wrong?

Thanks

Smdx

[crossrulz]

The build array is taking a lot of time because it is constantly grabbing more memory.  Instead, use the autoindex tunnel to build your array.  LabVIEW will preallocate the memory for the array and will run a lot faster.

[Wayne.C]

One thing that is absolutely killing you is the fact that you're reading a local variable 1765650 times each time you run this vi.

[dkfire]

I think you are doing it way to complicated. 

Try this:

NOTE: My local variable is somehow **bleep**ed. The reference control together with the property node should be a local variable.

[crossrulz · Accepted solution]

I haven't fully tested it, but see if this will work for you.  It is a lot simpler.

EDIT:  Ok, dkfire beat me to it.  At least we came up with the same solution independently.  I just use the autoindex tunnel where he preallocated the array and replaced elements.  Both ways will get you the same result.

[RavensFan]

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@dkfire wrote:

NOTE: My local variable is somehow **bleep**ed. The reference control together with the property node should be a local variable.

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Use the Code Capture Tool, it is so much better than the built-in LabVIEW snippet menu choice.  It doesn't break locals and references.

[lacVIEW]

Looks like you guys beat me to it, but I will post my solution anyways.

***EDIT: I need a shift register in the inner loop and should be autoindexing on the outer loop****

[crossrulz]

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@lacVIEW wrote:

Looks like you guys beat me to it, but I will post my solution anyways.

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That solution will not work.  For that method, you need a shift register in the inner loop and you should be autoindexing on the outer loop.