## Issue

A and B matrices will be different when i run the program

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

The output matrix (`C`

) should be the same dimension as matrix `A`

.

As title says, I’m trying to multiply each row from one matrix (`A`

) to every rows to another matrix (`B`

) and would like to sum them.

For example,

Dimension of `C = (2,3)`

```
C = [[A(0)*B(0) + A(1)*B(0)], [A(0)*B(1) + A(1)*B(1)],[A(0)*B(1) + A(1)*B(1)]]
```

I would like to know if there is a numpy function does that.

## Solution

Use numpy broadcasting:

```
C = (A * B[:, None]).sum(axis=1)
```

Output:

```
>>> C
array([[3, 3, 3],
[6, 6, 6],
[9, 9, 9]])
```

Answered By – richardec

Answer Checked By – Katrina (BugsFixing Volunteer)