

In [2]:

    
import numpy as np
a = np.array( [20,30,40,50] )
b = np.arange( 4 ) # [0, 1, 2, 3]
a-b









    Out[2]:





array([20, 29, 38, 47])



In [3]:

    
b**2









    Out[3]:





array([0, 1, 4, 9])



In [4]:

    
10*np.sin(a)









    Out[4]:





array([ 9.12945251, -9.88031624,  7.4511316 , -2.62374854])

dot vs. star



In [5]:

    
A = np.array( [[1,1],
...             [0,1]] )
B = np.array( [[2,0],
...             [3,4]] )



In [7]:

    
A*B # elementwise









    Out[7]:





array([[2, 0],
       [0, 4]])



In [8]:

    
np.dot(A, B) # matrix









    Out[8]:





array([[5, 4],
       [3, 4]])



In [ ]: