- added text inducating system's stability to z-Transformation

src/z_transform/z_transform.py

@@ -48,6 +48,7 @@ class zPlot():
         #self.filter = 'unit'
 
         self.H0_txt = None
+        self.systemIsStable = True
 
         self.length = 31
         self.n = np.linspace(-15, 15, num=self.length)
@@ -121,15 +122,15 @@ class zPlot():
         self.handles['axh'].set_title('Impulsantwort', fontsize='12')
         self.handles['axh'].set_xlabel(r'$\rightarrow n$')
         self.handles['axh'].set_ylabel(r'$\uparrow h(n)$')
-        self.pbzErrortxt = self.handles['axh'].text(-7, 3.25,
-                                                    'Zählergrad größer als Nennergrad. \nKeine Partialbruchzerlegung möglich!',
-                                                    fontsize=12, color='rot', visible=False, bbox=ient_wbbox)
         self.handles['containerh'] = ient_stem(self.handles['axh'], self.n, self.n)
         ient_axis(self.handles['axh'])
         self.handles['axH'] = plt.subplot(gs[1, 1])
         self.handles['axH'].set_title('Übertragungsfunktion', fontsize='12')
         self.handles['axH'].set_xlabel(r'$\rightarrow f$')
         self.handles['axH'].set_ylabel(r'$\uparrow |H(f)|$ [dB]')
+        self.stabilitytxt = self.handles['axH'].text(-6, 0,
+                                                    'Das System is nicht stabil!',
+                                                    fontsize=12, color='rot', visible=False, bbox=ient_wbbox)
         self.handles['lineH'], = self.handles['axH'].plot(self.f, self.f)
         ient_axis(self.handles['axH'])
         self.handles['axH'].spines['bottom'].set_position(('outward', 0))
@@ -421,8 +422,15 @@ class zPlot():
         ient_stem_set_ydata(self.handles['containerh'], np.real(h_n))
         ient_update_ylim(self.handles['axh'], h_n, 0.19, ymax=1e5)
 
+        self.systemIsStable = np.min(roc) < 1 and np.max(roc) > 1
+
         # update f-domain
+        if self.systemIsStable:
             H_f = ient_iz_Hf(self.f, self.H0, poles, zeroes, poles_order, zeroes_order, True)
+        else:
+            H_f = np.ones(self.f.shape) * -.5
+
+        self.stabilitytxt.set_visible(not self.systemIsStable)
+
         self.handles['lineH'].set_ydata(H_f)
         ient_update_ylim(self.handles['axH'], H_f, 1.9, ymax=1e5)
-