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Re: [Discuss-gnuradio] VOLK: fast way to log10()?
From: |
Marcus Müller |
Subject: |
Re: [Discuss-gnuradio] VOLK: fast way to log10()? |
Date: |
Wed, 16 Sep 2015 13:49:15 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 |
By the way, with a bit of approximation and a little acceptance for
errors in corner cases, log2 of a IEEE-754 float is simply it's exponent
+ log2(mantissa), with the later potentially being implementable using
lookup tables.
Also, VOLK does have a log2, kernel, volk_32f_log2_32f
Best regards,
Marcus
On 16.09.2015 06:50, Brian Padalino wrote:
> On Wed, Sep 16, 2015 at 12:24 AM, Dennis Glatting <address@hidden> wrote:
>> 1) Working with VOLK to learn VOLK.
>> 2) Having fun with vectors.
>> 3) Generating power data points for plotting across a selected
>> set of samples.
> Lastly, another alternative, if you wanted to utilize what is already
> there in VOLK, if you wanted to do something like 10*log10(x), you can
> also think of it as 10*log2(x)/log2(10) - rewritten to put the
> constants together - 10*log2(10)*log2(x), where 10*log2(10) is
> 3.01029995664.
>
> So convert a vector of floats into log2 then multiply a vector by a
> const that is equal to 10*log2(10) to get them to their final value.
> Not as efficient, potentially, but still an option if you want to
> learn VOLK.
>
> Brian
>
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- [Discuss-gnuradio] VOLK: fast way to log10()?, Dennis Glatting, 2015/09/15
- Re: [Discuss-gnuradio] VOLK: fast way to log10()?, Martin Braun, 2015/09/16
- Re: [Discuss-gnuradio] VOLK: fast way to log10()?, mleech, 2015/09/16
- Re: [Discuss-gnuradio] VOLK: fast way to log10()?, Dennis Glatting, 2015/09/16
- Re: [Discuss-gnuradio] VOLK: fast way to log10()?, West, Nathan, 2015/09/16
- Re: [Discuss-gnuradio] VOLK: fast way to log10()?, Dennis Glatting, 2015/09/16
- Re: [Discuss-gnuradio] VOLK: fast way to log10()?, Martin Braun, 2015/09/16
- Re: [Discuss-gnuradio] VOLK: fast way to log10()?, West, Nathan, 2015/09/17
- Re: [Discuss-gnuradio] VOLK: fast way to log10()?, Douglas Geiger, 2015/09/17
Re: [Discuss-gnuradio] VOLK: fast way to log10()?, Brian Padalino, 2015/09/16