wrong variable (dt does not exist, it's Ts)

awesomebytes · awesomebytes · commit 73ce2fec597d · 2014-01-05T15:31:02.000+01:00
Trying to use c2d with method 'zoh' fails with:

```
Traceback (most recent call last):
  File "system_example.py", line 56, in &lt;module&gt;
    syst_fake_dis = c2d(syst_fake, 0.01, method='zoh')
  File "/usr/local/lib/python2.7/dist-packages/control-0.6d-py2.7.egg/control/matlab.py", line 1519, in c2d
    return sample_system(sysc, Ts, method)
  File "/usr/local/lib/python2.7/dist-packages/control-0.6d-py2.7.egg/control/dtime.py", line 87, in sample_system
    sysd = TransferFunction(scipySysD[0][0],scipySysD[1], dt)
NameError: global name 'dt' is not defined
```
diff --git a/src/dtime.py b/src/dtime.py
@@ -79,12 +79,12 @@ def sample_system(sysc, Ts, method='matched'):
     elif method == 'tustin':
         sys = [sysc.num[0][0], sysc.den[0][0]]
         scipySysD = cont2discrete(sys, Ts, method='bilinear')
-        sysd = TransferFunction(scipySysD[0][0], scipySysD[1], dt)
+        sysd = TransferFunction(scipySysD[0][0], scipySysD[1], Ts)
 
     elif method == 'zoh':
         sys = [sysc.num[0][0], sysc.den[0][0]]
         scipySysD = cont2discrete(sys, Ts, method='zoh')
-        sysd = TransferFunction(scipySysD[0][0],scipySysD[1], dt)
+        sysd = TransferFunction(scipySysD[0][0],scipySysD[1], Ts)
 
     elif method == 'foh' or method == 'impulse':
         raise ValueError("Method not developed yet")
