adding 2 matrices

[rodrigo carvaja]

i'm having a little issue when adding2 matrices on python, according to my understanding the program should be:

m1=[[1,3,9],[5,6,3],[2,5,8]]
m2=[[1,3,9],[5,6,3],[2,5,8]]
n=3
def sumamat(a,b):
	z=[]
	for i in range (n):
		for j in range (n):
			x=m1[i][j]+m2[i][j]
			z.append(x)
		return z

print(sumamat(m1,m2))

being n the number of rows and columns since for my purposes, all the matrices are going to be N x N
as a result i get:
[2, 6, 18]
when i sould get:
[[2, 6, 18],[10,12,6],[4,10,16]]

i know i'm doing it the wrong way, i just don't know how to fix it, any help would be greatly appreciated!!

[Mariostg]

Look at the indention level of return x at line 10.
Your function stops when it executes the return.

Also, if you want a 3 by 3 matrix returned, you will have to provide indices to z when you populate it otherwise you will get a 1 by 9 matrix...

[bvdet]

Since you want a list of lists, you must append a list to z instead of an int. I also corrected your indentation

def sumamat(a,b):
    z=[]
    for i in range (n):
        tem = []
        for j in range (n):
            x=m1[i][j]+m2[i][j]
            tem.append(x)
        z.append(tem)
    return z

[rodrigo carvaja]

Thank you very much it works great!!! :)