Fast way to apply function on each element in vector

General JUCE discussion
1

Hello,
some time ago I discovered great FloatVectorOperations and I fell in love with it :slight_smile:

And lastly I got into situation that for each element in the array I need to calculate std::log10() and store those values in the same array, or at least copy them to another array.

Now I use basic for loop iterating through each element in the array and calculate std::log10() but I wonder if is there any better and faster way to do that?

I tried something like:

std::for_each(p, p+sizeOfArray, [](float &n) { n = std::log10(n); });

Where p is of course pointer to the first element of float array.

I have not made any extensive tests on very big arrays, but for my needs it looks like std::for_each is not much faster than iterating through each elements with standard for loop. While FloatVectorOperations makes really big difference in comparison with for loop.

So I would like to ask you if you know any better solution than classic for loop or std::for_each() ?

For any help great thanks in advance.

Best Regards

1 Like
2

Apple vDSP and Intel IPP both provide SIMD-accelerated log10 functions. You can write some code to call either vDSP or IPP, depending on the platform, in much the same way that juce FloatVectorOperarions is implemented

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Hello,
thanks, actually in vDSP I can’t find method which provides calculating exactly log10 function on vectors, but I found out method which converts vectors to decibels, and internal it uses log10. It’s enough for me, thanks. But if you know functions which calculates log10 then please let me know.

4

This is giving me low to mid single-digit percentage reductions in CPU usage across several of my compressor plugins on PC - not bad for a small amount of work! Thank you.