RE: Making a phase plot
- To: mathgroup at smc.vnet.net
- Subject: [mg62530] RE: [mg62516] Making a phase plot
- From: "David Park" <djmp at earthlink.net>
- Date: Sun, 27 Nov 2005 02:40:06 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Milind, The DrawGraphics package contains a BodePlot routine in the Examples section. It allows the breakpoint for ArcTan to be specified. Be aware that there is a problem with LogLinearPlot, and also LogLogPlot, in that the automatic point sampling is performed on a linear scale and not on a log scale. If you are plotting more than a few decades this causes serious undersampling of the low points and will result in an incorrect curve. It is difficult to overcome this simply by increasing the PlotPoints. The BodePlot corrects this and the Example section shows how to correct this in general. David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ From: Milind Gupta [mailto:milind.gupta at gmail.com] To: mathgroup at smc.vnet.net Hello, I wanted to plot the phase of a transfer function. I was doing it like this: LogLinearPlot[Phase[w], {w, 0, wmax}] Where Phase is calculated using the ArcTan function. The problem is tha= t the ArcTan function rounds up the result to positive values when the phase goes below -pi. But I want the phase to keep going negative values upto infinity. Is there a way to do this using some standard functions? Regards, Milind <Milind at usc.edu>