如何构造一个简单的矩阵并根据方程（numpy）更改值？

Question

My question is really simple. I have to make a 5*5 matrix and each i,j value should follow a formula of i+j

I have this so far: '''

 w = np.zeros(shape=(5,5)) print(w) for i in range(5): for j in range(5): w[i][j] == i**2+j print(w)

But Its just returning a 0 matrix right now what to do ?

Answer 1

Just change

w[i][j] == i**2+j

to (if you want to keep the formular)

w[i,j] = i**2+j

or use the formular from your question

w[i,j] = i+j

If you want to get rid of the loops, you can use numpy

w = np.arange(5)
w = np.add.outer(w ** 2, w)
print(w)

Out:

[[ 0  1  2  3  4]
 [ 1  2  3  4  5]
 [ 4  5  6  7  8]
 [ 9 10 11 12 13]
 [16 17 18 19 20]]