bench: add benchmark of switch between np.array and np.matrix

benchmarks/bench-switch.py

+from __future__ import print_function
+
+import eigenpy
+import numpy as np
+
+import time
+import timeit
+
+from IPython import get_ipython
+ipython = get_ipython()
+
+quat = eigenpy.Quaternion()
+a = [0., 0., 0.]
+
+cmd1 = "timeit np.array(a)"
+print("\n")
+print(cmd1)
+ipython.magic(cmd1)
+print("\n")
+
+cmd2 = "timeit np.matrix(a)"
+print(cmd2)
+ipython.magic(cmd2)
+print("\n")
+
+eigenpy.switchToNumpyMatrix()
+print("----------------------")
+print("switch to numpy matrix")
+print("----------------------")
+print("\n")
+
+cmd3 = "timeit quat.coeffs()"
+print(cmd3)
+ipython.magic(cmd3)
+print("\n")
+
+eigenpy.switchToNumpyArray()
+print("---------------------")
+print("switch to numpy array")
+print("---------------------")
+print("\n")
+
+cmd4 = "timeit quat.coeffs()"
+print(cmd4)
+ipython.magic(cmd4)
+print("\n")