DOC: Tweak the backlash_sum demo.

Author: WarrenWeckesser

README.md

@@ -1757,10 +1757,11 @@ array([ 0.    ,  0.025 ,  0.25  ,  0.85  ,  1.    ,  0.9875,  0.45  , -0.75  ])
 
 -----
 
-Another example is in the script `backlash_sum_demo.py` in the `examples` directory.
-It passes two cycles of a sine wave through a Prandtl-Ishlinskii model with three
-backlash operations.  The weights are `w = [0.25, 1.0, 0.5]`, the deadband values
-are `[0.5, 1.0, 2.0]` and the initial values are all zero.
+Another example is in the script `backlash_sum_demo.py` in the `examples`
+directory. It passes two cycles of a sine wave with amplitude 2 through a
+Prandtl-Ishlinskii model with three backlash operations.  The weights are
+`w = [0.125, 0.25, 0.25]`, the deadband values are `[0.5, 1.0, 1.5]`, and
+the initial values are all zero.
 
 ![Backlash_sum plot](https://github.com/WarrenWeckesser/ufunclab/blob/main/examples/backlash_sum_demo_x_vs_t.png)
 

examples/backlash_sum_demo.py

@@ -5,21 +5,21 @@
 
 
 t = np.linspace(0, 4*np.pi, 1000)
-x = np.sin(t)
+x = 2*np.sin(t)
 
-w = np.array([0.25, 1.0, 1.25])
-deadband = np.array([0.5, 1.0, 2.0])
+w = np.array([0.125, 0.25, 0.25])
+deadband = np.array([0.5, 1.0, 1.5])
 initial = np.zeros(3)
 
 y, final = backlash_sum(x, w, deadband, initial)
 
-
 plt.figure(figsize=(6, 4))
 plt.plot(t, x, linewidth=2, label='x(t)')
 plt.plot(t, y, '--', linewidth=2, label='backlash_sum(x(t))')
 plt.xlabel('t')
 plt.title('backlash_sum')
-plt.legend(shadow=True)
+plt.legend(shadow=True, loc='upper right')
+plt.xlim(-0.99, 14.5)
 plt.grid(alpha=0.6)
 plt.savefig('backlash_sum_demo_x_vs_t.png')