Re: [Discuss-gnuradio] VOLK: fast way to log10()?

[Brian Padalino]

On a side note, this is extremely impressive and I wish I knew about it sooner:

  https://software.intel.com/sites/landingpage/IntrinsicsGuide/

There's a few different log10_ps (packed single) functions in there.

Brian

On Wed, Sep 16, 2015 at 12:24 AM, Dennis Glatting <address@hidden> wrote:
> On Tue, 2015-09-15 at 23:35 -0400, Marcus D. Leech wrote:
>> On 09/15/2015 11:15 PM, Dennis Glatting wrote:
>> > With the VOLK library, is there a way to compute the log10() of
>> > each
>> > 32f in a buffer?
>> >
>> > That is:
>> >
>> >   for( int i = 0; i < num; ++i )
>> >     buf[i] = std::log10( buf[i]);
>> >
>> > I only see log2() in the library but don't know if there is an easy
>> > way
>> > to compute log10().
>> >
>> >
>> > Thanks.
>> Define "fast".
>>
>
> Faster than the code fragment above.
>
> I see log2(), pow(), sin(), and other kernels in the library and
> /assumed/ there must be some way of log10() if only through a
> combination of kernel calls.
>
>
>> Ordinarily, one does a log10 to convert into engineering units at the
>> back of, for example, a power-measurement chain.
>>
>> There's usually no reason to do that in the middle of a flow-graph,
>> where things can stay in linear units.
>>
>
> 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.
>
>
>>
>>
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