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Re: Engineering requests

  • To: mathgroup at smc.vnet.net
  • Subject: [mg125483] Re: Engineering requests
  • From: "McHale, Paul" <Paul.McHale at excelitas.com>
  • Date: Thu, 15 Mar 2012 00:31:20 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <201203130804.DAA12797@smc.vnet.net>



Paul McHale  |  Electrical Engineer, Energetics Systems  |  Excelitas Technologies Corp.

Phone:   +1 937.865.3004   |   Fax:  +1 937.865.5170   |   Mobile:   +1 937.371.2828
1100 Vanguard Blvd, Miamisburg, Ohio 45342-0312 USA
Paul.McHale at Excelitas.com
www.excelitas.com

It's not the re-formulation I mind, it's there error I introduce when doing it :).  We make an assumption that the max/min answer will exist when using some permutation of max/min variables.  For the cases we deal most with, this is true.  It would be easiest enough to add a nominal value to ensure max/min answer is some permutation of the max/min of the input variables.  Not fool proof in higher order issues.  If the test fails, then other techniques (monte carlo) would be used.

The simplest answer would be:

Eq=5*R2/(R1+R2)
TolerancePermutations[Eq,R1->{min,nom,max}, R2->{min,nom,max}]

Out: {Min -> Num1, Max -> Num2}

Or

>> peak value found at nominal tolerance, recommend other methods
Out: {Min -> Num1, Max -> indeterminite}

Paul


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Thank you

-----Original Message-----
From: Dana DeLouis [mailto:dana01 at me.com]
Sent: Tuesday, March 13, 2012 4:04 AM
To: mathgroup at smc.vnet.net
Subject: [mg125483] Re: Engineering requests

On Mar 12, 5:07 am, "McHale, Paul" <Paul.McH... at excelitas.com> wrote:

> The interval function looks a little to foreign to this intended purpose.  Slight changes in the representation you chose seems to break it quickly.

<snip>

> > (* using table   (correct answers)    *)
> > R1=R1int;
> > R2=R2int;
> > Table[5/(Ra+Rb) Rb,{Ra,R1},{Rb,R2}]// Max
> > Table[5/(Ra+Rb) Rb,{Ra,R1},{Rb,R2}]// Min
>
> > Out[3]= 1.34146
> > Out[4]= 0.985401

vs:

5./(1+r1/r2)
Interval[{0.985401,1.34146}]

Hi.  Not sure what was changed, but I believe one needs to eliminate duplicate variables.
I think you need to reduce the equation so that each interval occurs once.

Another way might be...
The numbers used are the min and max of the intervals involved.

5. * 27000 / (27000+110000)
0.985401

5.*  33000 / (90000+33000)
1.34146

= = = = = = = = = =
HTH   :>)
Dana DeLouis
= = = = = = = = = =




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