Re: Optimize pow() function

From	Don Y <blockedofcourse@foo.invalid>
Newsgroups	comp.arch.embedded
Subject	Re: Optimize pow() function
Date	2016-09-23 12:12 -0700
Organization	A noiseless patient Spider
Message-ID	<ns3uri$oql$1@dont-email.me> (permalink)
References	<ns0mo1$7j2$1@dont-email.me> <ns0p5g$ggu$1@dont-email.me> <ns1hbm$c75$1@dont-email.me> <ns1jmm$jk0$1@dont-email.me> <ns2l98$789$1@dont-email.me>

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On 9/23/2016 12:23 AM, pozz wrote:
>> What is your *load*?  If purely resistive, does it have a temperature
>> coefficient?  (e.g., if you left it operating at Pmax, would you see
>> changes)
>>
>> In operation, do you expect the load to be "static"?  Or, time varying?
>> Does the load's impedance change based on how *it* is driven?  etc.
>
> I don't care the load.  I'm only working on the power transducer.  If the load
> changes (because of temperature, degradation, ...), the output signal of
> transducer will change accordingly and the power reading will change too.

(sigh)  You really don't understand the problem you're trying to solve.

I have a voltmeter, here, good to 5-1/2 digits.  It was calibrated 4 minutes
ago to an NBS traceable reference.  It's sitting in a temperature controlled
housing.  yada-yada-yada-yada.

It is presently displaying 1.92341 volts.  To what "power" does that
correspond?

[pull black curtain to hide my actions...]

Now, it's displaying 1.84421 volts.  What power level does THIS represent?
Is it MORE or LESS than the power above??  (think carefully before
answering).

How does your "professional instrument" (acting as your authoritative
reference) measure the power in the load?  Why do you trust *it* -- yet
KNOW that your measurements are incorrect?  What does *it* know that
you don't?  What is it *doing* that you aren't?

Thread

Optimize pow() function pozz <pozzugno@gmail.com> - 2016-09-22 15:36 +0200
  Re: Optimize pow() function Don Y <blockedofcourse@foo.invalid> - 2016-09-22 07:17 -0700
    Re: Optimize pow() function pozz <pozzugno@gmail.com> - 2016-09-22 23:10 +0200
      Re: Optimize pow() function rickman <gnuarm@gmail.com> - 2016-09-22 17:31 -0400
        Re: Optimize pow() function lasselangwadtchristensen@gmail.com - 2016-09-22 14:44 -0700
        Re: Optimize pow() function pozz <pozzugno@gmail.com> - 2016-09-23 09:03 +0200
          Re: Optimize pow() function Paul Rubin <no.email@nospam.invalid> - 2016-09-23 00:17 -0700
          Re: Optimize pow() function Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2016-09-23 22:45 +0300
      Re: Optimize pow() function rickman <gnuarm@gmail.com> - 2016-09-22 17:44 -0400
        Re: Optimize pow() function pozz <pozzugno@gmail.com> - 2016-09-23 09:08 +0200
          Re: Optimize pow() function rickman <gnuarm@gmail.com> - 2016-09-24 01:54 -0400
      Re: Optimize pow() function Don Y <blockedofcourse@foo.invalid> - 2016-09-22 14:50 -0700
        Re: Optimize pow() function pozz <pozzugno@gmail.com> - 2016-09-23 09:23 +0200
          Re: Optimize pow() function Don Y <blockedofcourse@foo.invalid> - 2016-09-23 00:32 -0700
          Re: Optimize pow() function Evgeny Filatov <e.v.filatov@ieee.org> - 2016-09-23 12:56 +0300
            Re: Optimize pow() function Don Y <blockedofcourse@foo.invalid> - 2016-09-23 10:41 -0700
          Re: Optimize pow() function Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2016-09-23 21:07 +0200
          Re: Optimize pow() function Don Y <blockedofcourse@foo.invalid> - 2016-09-23 12:12 -0700
    Re: Optimize pow() function pozz <pozzugno@gmail.com> - 2016-09-22 23:12 +0200
      Re: Optimize pow() function Don Y <blockedofcourse@foo.invalid> - 2016-09-22 14:58 -0700
  Re: Optimize pow() function Tim Wescott <tim@seemywebsite.com> - 2016-09-22 10:01 -0500
    Re: Optimize pow() function Jack <jack4747@gmail.com> - 2016-09-22 08:08 -0700
      Re: Optimize pow() function Tim Wescott <seemywebsite@myfooter.really> - 2016-09-22 11:53 -0500
        Re: Optimize pow() function pippo2@disney.com (Jack) - 2016-09-22 21:12 +0200
          Re: Optimize pow() function lasselangwadtchristensen@gmail.com - 2016-09-22 13:12 -0700
          Re: Optimize pow() function Tim Wescott <seemywebsite@myfooter.really> - 2016-09-22 15:51 -0500
    Re: Optimize pow() function pozz <pozzugno@gmail.com> - 2016-09-22 23:15 +0200
      Re: Optimize pow() function Tim Wescott <seemywebsite@myfooter.really> - 2016-09-22 17:52 -0500
      Re: Optimize pow() function David Brown <david.brown@hesbynett.no> - 2016-09-23 09:32 +0200
    Re: Optimize pow() function David Brown <david.brown@hesbynett.no> - 2016-09-23 09:28 +0200
      Re: Optimize pow() function Paul Rubin <no.email@nospam.invalid> - 2016-09-23 00:47 -0700
        Re: Optimize pow() function David Brown <david.brown@hesbynett.no> - 2016-09-23 11:05 +0200
        Re: Optimize pow() function Tim Wescott <tim@seemywebsite.com> - 2016-09-23 11:44 -0500
  Re: Optimize pow() function Jack <jack4747@gmail.com> - 2016-09-22 23:15 -0700
    Re: Optimize pow() function Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2016-09-23 20:49 +0200
  Re: Optimize pow() function Richard Damon <Richard@Damon-Family.org> - 2016-09-25 06:50 -0400
    Re: Optimize pow() function Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2016-09-25 16:36 +0300
      Re: Optimize pow() function Chris <xxx.syseng.yyy@gfsys.co.uk> - 2016-09-26 17:30 +0000
        Re: Optimize pow() function Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2016-09-26 21:49 +0300
      Re: Optimize pow() function pozz <pozzugno@gmail.com> - 2016-09-26 23:30 +0200
        Re: Optimize pow() function Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2016-09-27 18:58 +0300
  Re: Optimize pow() function Robert Wessel <robertwessel2@yahoo.com> - 2016-09-26 22:44 -0500

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