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MathGroup Archive 2005

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Re: Re: bode diagram

  • To: mathgroup at smc.vnet.net
  • Subject: [mg57190] Re: [mg57151] Re: bode diagram
  • From: DrBob <drbob at bigfoot.com>
  • Date: Fri, 20 May 2005 04:43:26 -0400 (EDT)
  • References: <d64fjl$9gl$1@smc.vnet.net> <200505190708.DAA13088@smc.vnet.net>
  • Reply-to: drbob at bigfoot.com
  • Sender: owner-wri-mathgroup at wolfram.com

Thanks! I think that explains the dips and bumps I was missing, compared to the website plots.

Bobby

On Thu, 19 May 2005 03:08:22 -0400 (EDT), Mariusz Jankowski <mjankowski at usm.maine.edu> wrote:

> Bob, the argument of your function h must be I * s in both the magnitude
> plot and the phase plot. You are therefore making a mistake in ALL of your
> magnitude plots.
>
> Mariusz
>
>
>
>>>> DrBob<drbob at bigfoot.com> 05/14/05 5:15 AM >>>
> I used the code below for each example at the link:
>
> http://www.swarthmore.edu/NatSci/echeeve1/Ref/Bode/BodeRules.html#Examples
>
> In several cases I got what appears to be the same result as pictured at the
> link, but in other cases I got very different plots. The fourth example is
> particularly strange. Am I doing this wrong?
>
> I'm plotting magnitude and phase on a single plot in each case, and I'm ONLY
> plotting the exact curves -- assuming I have the right formulae for them. I
> see no point in approximate plotting techniques, with exact plots readily
> available.
>
> Needs["Graphics`Graphics`"]
> SetOptions[LogLinearPlot, PlotStyle ->
>      {Red, Blue}, PlotRange -> All,
>     ImageSize -> 500];
> db = 20*Log[10, Abs[#1]] & ;
>
> Clear[h]
> h[s_] = 100/(s + 20);
> LogLinearPlot[{db[h[s]], Arg[h[I*s]]*(180/Pi)},
>     {s, 1, 10^3}];
>
> h[s_] = (100*s + 100)/(s^2 + 110*s + 1000);
> LogLinearPlot[{db[h[s]], Arg[h[I*s]]*(180/Pi)},
>     {s, 10^(-2), 10^4}];
>
> h[s_] = 10*((s + 10)/(s^2 + 3*s));
> LogLinearPlot[{db[h[s]], Arg[h[I*s]]*(180/Pi)},
>     {s, 10^(-1), 10^3}];
>
> h[s_] = (-100*s)/(s^3 + 12*s^2 + 21*s + 10);
> LogLinearPlot[{db[h[s]], Arg[h[I*s]]*(180/Pi)},
>     {s, 10^(-2), 10^3}];
>
> h[s_] = 30*((s + 10)/(s^2 + 3*s + 50));
> LogLinearPlot[{db[h[s]], Arg[h[I*s]]*(180/Pi)},
>     {s, 10^(-1), 10^3}];
>
> h[s_] = 4*((s^2 + s + 25)/(s^3 + 100*s^2));
> LogLinearPlot[{db[h[s]], Arg[h[I*s]]*(180/Pi)},
>     {s, 10^(-1), 10^3}];
>
> Bobby
>
> From: Pratik Desai <pdesai1 at umbc.edu>
To: mathgroup at smc.vnet.net
> References: <200505120633.CAA08967 at smc.vnet.net>
>
> David Park wrote:
>
>> I'm fairly certain it could be done with Mathematica if you would only
> tell
>> us what a bode diagram is and give us some sample data of function that
> you
>> want to plot in the diagram.
>>
>> David Park
>> djmp at earthlink.net
>> http://home.earthlink.net/~djmp/
>>
>> From: GaLoIs [mailto:lanellomancante at inwind.it]
To: mathgroup at smc.vnet.net
>>
>>
>> hi, like plotting simple bode diagrams of systems. could you give me some
>> information about it? i can do it with another program, but i'd like to
> see
>> how mathematica works
>> thank you
>>
>>
>>
>>
>>
>>
>>
> Here is a nice example from a website I found.
>
> *http://www.swarthmore.edu/NatSci/echeeve1/Ref/Bode/Bode.html*
>
>



-- 
DrBob at bigfoot.com


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