multiply a matrix by an integer in python
Question: I know how to multiply two matrices(under a class). Below I show my code.
However I can not seem to figure out how to multiply a matrix and an integer
in Python.

**Update** : Example of a matrix.

    
    
    L=[[1,2],[3,4],[5,6]]
    3*L
    # [[1,6],[9,12],[15,18]]
    
    def __mul__(self,other):
        '''this will multiply two predefined matrices where the number of
        columns in the first is equal to the number of rows in the second.'''
        L=self.L
        L2=other.L
        result=[]
        if len(L[0])==len(L2):
            for i in range(len(L)):
                row=[]
                for j in range(len(L2[0])):
                    var=0 
                    for k in range(len(L2)):
                        var=var+L[i][k]*L2[k][j]
                    row=row+[var]
                result = result+[row]
            return matrix(result)
        else:
            raise ValueError('You may not only multiply m*n * n*q matrices.')
    


Answer: Depends on what you mean by `matrix`, but with [numpy](http://numpy.org/), it
would be just like:

    
    
    import numpy as np
    
    M= np.arange(9).reshape(3, 3)
    # array([[0, 1, 2],
    #        [3, 4, 5],
    #        [6, 7, 8]])
    2* M
    # array([[ 0,  2,  4],
    #        [ 6,  8, 10],
    #        [12, 14, 16]])
    

or

    
    
    M= np.matrix([[1, 2], [3, 4]])
    # matrix([[1, 2],
    #         [3, 4]])
    2* M
    # matrix([[2, 4],
    #         [6, 8]])
    

