Re: bode diagram

*To*: mathgroup at smc.vnet.net*Subject*: [mg57151] Re: bode diagram*From*: "Mariusz Jankowski" <mjankowski at usm.maine.edu>*Date*: Thu, 19 May 2005 03:08:22 -0400 (EDT)*Organization*: University of Southern Maine*References*: <d64fjl$9gl$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

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

**Follow-Ups**:**Re: Re: bode diagram***From:*DrBob <drbob@bigfoot.com>