[python-control-discuss] SF.net python-control commit:[303] trunk/src/margins.py

[<re...@us...>]

Revision: 303
          http://sourceforge.net/p/python-control/code/303
Author:   repa
Date:     2014-07-06 17:06:44 +0000 (Sun, 06 Jul 2014)
Log Message:
-----------
Slightly increase the epsilon value for margin computation frequency, 
many type 2 systems (on Windows, 32 bit pythonxy, but not on 64 bit Linux
which I tested on) got cross over margins calculated at frequencies 
around 1e-11

Modified Paths:
--------------
    trunk/src/margins.py

Modified: trunk/src/margins.py
===================================================================
--- trunk/src/margins.py	2014-06-16 08:38:23 UTC (rev 302)
+++ trunk/src/margins.py	2014-07-06 17:06:44 UTC (rev 303)
@@ -80,13 +80,14 @@
 # idea for the frequency data solution copied/adapted from
 # https://github.com/alchemyst/Skogestad-Python/blob/master/BODE.py
 # Rene van Paassen <ren...@gm...>
-def stability_margins(sysdata, deg=True, returnall=False, epsw=1e-12):
+def stability_margins(sysdata, deg=True, returnall=False, epsw=1e-10):
     """Calculate gain, phase and stability margins and associated
     crossover frequencies.
     
     Usage
     -----
-    gm, pm, sm, wg, wp, ws = stability_margins(sysdata, deg=True)
+    gm, pm, sm, wg, wp, ws = stability_margins(sysdata, deg=True,
+                                               returnall=False, epsw=1e-10)
     
     Parameters
     ----------
@@ -101,7 +102,7 @@
     returnall=False: boolean
         If true, return all margins found. Note that for frequency data or
         FRD systems, only one margin is found and returned. 
-    epsw=1e-12: float
+    epsw=1e-10: float
         frequencies below this value are considered static gain, and not
         returned as margin.
        
@@ -114,7 +115,7 @@
         one crossover frequency is detected, returns the lowest corresponding
         margin. 
         When requesting all margins, the return values are array_like, 
-        and all margins are returns for linear systems not equal to FRD
+        and all margins are returned for linear systems not equal to FRD
         """
 
     try: